Bump version

- Remove redundant preservation of cobalt lib constructors. We use
   lambdas now, so this is no longer needed.
 - Fix Java crypto lib not being included.

.editorconfig

@@ -11,5 +11,8 @@ insert_final_newline = true
 [*.md]
 trim_trailing_whitespace = false
 
+[*.sexp]
+indent_size = 2
+
 [*.properties]
 insert_final_newline = false

.github/workflows/main-ci.yml

@@ -0,0 +1,33 @@
+name: Build
+
+on: [push, pull_request]
+
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v1
+
+    - name: Set up JDK 1.8
+      uses: actions/setup-java@v1
+      with:
+        java-version: 1.8
+
+    - name: Build with Gradle
+      run: ./gradlew build --no-daemon
+
+  lint-lua:
+    name: Lint Lua
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v1
+
+    - name: Lint Lua code
+      run: |
+        test -d bin || mkdir bin
+        test -f bin/illuaminate || wget -q -Obin/illuaminate https://squiddev.cc/illuaminate/bin/illuaminate
+        chmod +x bin/illuaminate
+        bin/illuaminate lint

.luacheckrc

@@ -1,34 +0,0 @@
-std = "max"
-
-ignore = {
-    -- Allow access to undefined globals or their fields. In the future we'll
-    -- define all of CC's globals within this file
-    '113', '143',
-
-    -- FIXME: Ignore unused arguments and loop variables
-    '212', '213',
-
-    -- Disable line is too long for now. It would be possible to clean
-    -- this up in the future.
-    '631',
-}
-
--- Only run the linter on ROM and bios for now, as the treasure disks
--- are largely unsupported.
-include_files = {
-    'src/main/resources/assets/computercraft/lua/rom',
-    'src/main/resources/assets/computercraft/lua/bios.lua'
-}
-
-files['src/main/resources/assets/computercraft/lua/bios.lua'] = {
-    -- Allow declaring and mutating globals
-    allow_defined_top = true,
-    ignore = { '112', '121', '122', '131', '142' },
-}
-
-files['src/main/resources/assets/computercraft/lua/rom/apis'] = {
-    -- APIs may define globals on the top level. We'll ignore unused globals,
-    -- as obviously they may be used outside that API.
-    allow_defined_top = true,
-    ignore = { '131' },
-}

.travis.yml

@@ -1,14 +0,0 @@
-language: java
-
-script: ./gradlew build --no-daemon
-
-before_cache:
-  - rm -f  $HOME/.gradle/caches/modules-2/modules-2.lock
-  - rm -fr $HOME/.gradle/caches/*/plugin-resolution/
-cache:
-  directories:
-    - $HOME/.gradle/caches/
-    - $HOME/.gradle/wrapper/s
-
-jdk:
-    - oraclejdk8

README.md

@@ -1,5 +1,5 @@
 # ![CC: Tweaked](logo.png)
-[![Current build status](https://travis-ci.org/SquidDev-CC/CC-Tweaked.svg?branch=master)](https://travis-ci.org/SquidDev-CC/CC-Tweaked "Current build status") [![Download CC: Tweaked on CurseForge](https://cf.way2muchnoise.eu/title/cc-tweaked.svg)](https://minecraft.curseforge.com/projects/cc-tweaked "Download CC: Tweaked on CurseForge")
+[![Current build status](https://github.com/SquidDev-CC/CC-Tweaked/workflows/Build/badge.svg)](https://github.com/SquidDev-CC/CC-Tweaked/actions "Current build status") [![Download CC: Tweaked on CurseForge](http://cf.way2muchnoise.eu/title/cc-tweaked.svg)](https://minecraft.curseforge.com/projects/cc-tweaked "Download CC: Tweaked on CurseForge")
 
 CC: Tweaked is a fork of [ComputerCraft](https://github.com/dan200/ComputerCraft), adding programmable computers,
 turtles and more to Minecraft.

build.gradle

@@ -5,7 +5,7 @@ buildscript {
         jcenter()
         maven {
             name = "forge"
-            url = "http://files.minecraftforge.net/maven"
+            url = "https://files.minecraftforge.net/maven"
         }
     }
     dependencies {
@@ -45,7 +45,7 @@ minecraft {
 repositories {
     maven {
         name "JEI"
-        url "http://dvs1.progwml6.com/files/maven"
+        url "https://dvs1.progwml6.com/files/maven"
     }
     maven {
         name "SquidDev"
@@ -57,7 +57,11 @@ repositories {
     }
     maven {
         name "Amadornes"
-        url "http://maven.amadornes.com/"
+        url "https://maven.amadornes.com/"
+    }
+    maven {
+        name "CraftTweaker"
+        url "https://maven.blamejared.com/"
     }
 }
 
@@ -68,22 +72,25 @@ configurations {
 }
 
 dependencies {
-    checkstyle "com.puppycrawl.tools:checkstyle:8.21"
+    checkstyle "com.puppycrawl.tools:checkstyle:8.25"
 
+    deobfProvided "CraftTweaker2:CraftTweaker2-MC1120-Main:1.12-4.1.20.554"
+    deobfProvided "MCMultiPart2:MCMultiPart:2.5.3"
     deobfProvided "mezz.jei:jei_1.12.2:4.15.0.269:api"
     deobfProvided "pl.asie:Charset-Lib:0.5.4.6"
-    deobfProvided "MCMultiPart2:MCMultiPart:2.5.3"
 
     runtime "mezz.jei:jei_1.12.2:4.15.0.269"
 
     shade 'org.squiddev:Cobalt:0.5.0-SNAPSHOT'
 
-    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.1.0'
-    testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.1.0'
+    testImplementation 'org.junit.jupiter:junit-jupiter-api:5.4.2'
+    testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.4.2'
 
     deployerJars "org.apache.maven.wagon:wagon-ssh:3.0.0"
 }
 
+// Compile tasks
+
 javadoc {
     include "dan200/computercraft/api/**/*.java"
 }
@@ -102,6 +109,14 @@ jar {
     from configurations.shade.collect { it.isDirectory() ? it : zipTree(it) }
 }
 
+[compileJava, compileTestJava].forEach {
+    it.configure {
+        options.compilerArgs << "-Xlint" << "-Xlint:-processing" << "-Werror"
+    }
+}
+
+
+
 import java.nio.charset.StandardCharsets
 import java.nio.file.*
 import java.util.zip.*
@@ -122,6 +137,7 @@ task proguard(type: ProGuardTask, dependsOn: jar) {
 
     // Add the main runtime jar and all non-shadowed dependencies
     libraryjars "${System.getProperty('java.home')}/lib/rt.jar"
+    libraryjars "${System.getProperty('java.home')}/lib/jce.jar"
     doFirst {
         sourceSets.main.compileClasspath
             .filter { !it.name.contains("Cobalt") }
@@ -136,9 +152,6 @@ task proguard(type: ProGuardTask, dependsOn: jar) {
 
     // Preserve ComputerCraft classes - we only want to strip shadowed files.
     keep 'class dan200.computercraft.** { *; }'
-
-    // Preserve the constructors in Cobalt library class, as we init them via reflection
-    keepclassmembers 'class org.squiddev.cobalt.lib.** { <init>(...); }'
 }
 
 task proguardMove(dependsOn: proguard) {
@@ -233,7 +246,14 @@ task compressJson(dependsOn: extractAnnotationsJar) {
 
 assemble.dependsOn compressJson
 
-/* Check tasks */
+// Check tasks
+
+test {
+    useJUnitPlatform()
+    testLogging {
+        events "skipped", "failed"
+    }
+}
 
 license {
     mapping("java", "SLASHSTAR_STYLE")
@@ -257,6 +277,13 @@ license {
     }
 }
 
+gradle.projectsEvaluated {
+    tasks.withType(LicenseFormat) {
+        outputs.upToDateWhen { false }
+    }
+}
+
+
 task licenseAPI(type: LicenseCheck);
 task licenseFormatAPI(type: LicenseFormat);
 [licenseAPI, licenseFormatAPI].forEach {
@@ -267,7 +294,7 @@ task licenseFormatAPI(type: LicenseFormat);
     }
 }
 
-/* Upload tasks */
+// Upload tasks
 
 task checkRelease {
     group "upload"
@@ -307,6 +334,7 @@ task checkRelease {
         if (!ok) throw new IllegalStateException("Could not check release")
     }
 }
+check.dependsOn checkRelease
 
 curseforge {
     apiKey = project.hasProperty('curseForgeApiKey') ? project.curseForgeApiKey : ''
@@ -378,7 +406,9 @@ githubRelease {
     token project.hasProperty('githubApiKey') ? project.githubApiKey : ''
     owner 'SquidDev-CC'
     repo 'CC-Tweaked'
-    targetCommitish { Grgit.open(dir: '.').branch.current().name }
+    try {
+        targetCommitish = Grgit.open(dir: '.').branch.current().name
+    } catch(Exception ignored) { }
 
     tagName "v${mc_version}-${mod_version}"
     releaseName "[${mc_version}] ${mod_version}"
@@ -399,22 +429,5 @@ task uploadAll(dependsOn: uploadTasks) {
     description "Uploads to all repositories (Maven, Curse, GitHub release)"
 }
 
-test {
-    useJUnitPlatform()
-    testLogging {
-        events "passed", "skipped", "failed"
-    }
-}
-
-gradle.projectsEvaluated {
-    tasks.withType(JavaCompile) {
-        options.compilerArgs << "-Xlint" << "-Xlint:-processing" << "-Werror"
-    }
-
-    tasks.withType(LicenseFormat) {
-        outputs.upToDateWhen { false }
-    }
-}
-
 runClient.outputs.upToDateWhen { false }
 runServer.outputs.upToDateWhen { false }

config/checkstyle/checkstyle.xml

@@ -14,9 +14,7 @@
         <!-- Annotations -->
         <module name="AnnotationLocation" />
         <module name="AnnotationUseStyle" />
-        <module name="MissingDeprecated">
-            <property name="skipNoJavadoc" value="true" />
-        </module>
+        <module name="MissingDeprecated" />
         <module name="MissingOverride" />
 
         <!-- Blocks -->
@@ -57,6 +55,9 @@
         <module name="SimplifyBooleanReturn" />
         <module name="StringLiteralEquality" />
         <module name="UnnecessaryParentheses" />
+        <module name="UnnecessarySemicolonAfterTypeMemberDeclaration" />
+        <module name="UnnecessarySemicolonInTryWithResources" />
+        <module name="UnnecessarySemicolonInEnumeration" />
 
         <!-- Imports -->
         <module name="CustomImportOrder" />
@@ -65,10 +66,16 @@
         <module name="UnusedImports" />
 
         <!-- Javadoc -->
+        <!-- TODO: Missing* checks for the dan200.computercraft.api package? -->
         <module name="AtclauseOrder" />
-        <!-- TODO: Cleanup our documentation before enabling JavadocMethod, JavadocStyle, JavadocType and SummaryJavadoc. -->
+        <module name="InvalidJavadocPosition" />
+        <module name="JavadocBlockTagLocation" />
+        <module name="JavadocMethod"/>
+        <module name="JavadocType"/>
+        <module name="JavadocStyle" />
         <module name="NonEmptyAtclauseDescription" />
         <module name="SingleLineJavadoc" />
+        <module name="SummaryJavadocCheck"/>
 
         <!-- Misc -->
         <module name="ArrayTypeStyle" />
@@ -155,5 +162,8 @@
 
     <module name="FileTabCharacter" />
     <module name="NewlineAtEndOfFile" />
+    <module name="RegexpSingleline">
+        <property name="format" value="\s+$"/>
+        <property name="message" value="Trailing whitespace"/>
+    </module>
 </module>
-

config/checkstyle/suppressions.xml

@@ -3,11 +3,10 @@
     "-//Checkstyle//DTD SuppressionFilter Configuration 1.2//EN"
     "https://checkstyle.org/dtds/suppressions_1_2.dtd">
 <suppressions>
-    <!-- Has a public m_label field. We need to check if this is used in other projects before renaming it. -->
-    <suppress checks="MemberName" files=".*[\\/]TileComputerBase.java"
-        message="Name 'm_label' must match pattern .*" />
-
     <!-- All the config options and method fields. -->
     <suppress checks="StaticVariableName" files=".*[\\/]ComputerCraft.java" />
     <suppress checks="StaticVariableName" files=".*[\\/]ComputerCraftAPI.java" />
+
+    <!-- Do not check for missing package Javadoc. -->
+    <suppress checks="JavadocStyle" files=".*[\\/]package-info.java" />
 </suppressions>

gradle.properties

@@ -1,5 +1,5 @@
 # Mod properties
-mod_version=1.83.1
+mod_version=1.86.0
 
 # Minecraft properties
 mc_version=1.12.2

illuaminate.sexp

@@ -0,0 +1,28 @@
+; -*- mode: Lisp;-*-
+
+(sources
+  /src/main/resources/assets/computercraft/lua/bios.lua
+  /src/main/resources/assets/computercraft/lua/rom/
+  /src/test/resources/test-rom)
+
+(at /
+  (linters
+    ;; It'd be nice to avoid this, but right now there's a lot of instances of
+    ;; it.
+    -var:set-loop
+
+    ;; It's useful to name arguments for documentation, so we allow this. It'd
+    ;; be good to find a compromise in the future, but this works for now.
+    -var:unused-arg))
+
+;; We disable the unused global linter in bios.lua and the APIs. In the future
+;; hopefully we'll get illuaminate to handle this.
+(at
+  (/src/main/resources/assets/computercraft/lua/bios.lua
+   /src/main/resources/assets/computercraft/lua/rom/apis/)
+  (linters -var:unused-global)
+  (lint
+    (allow-toplevel-global true)))
+
+;; These warnings are broken right now
+(at (bios.lua worm.lua) (linters -control:unreachable))

src/main/java/dan200/computercraft/ComputerCraft.java

@@ -72,9 +72,7 @@ import net.minecraft.util.math.BlockPos;
 import net.minecraft.world.IBlockAccess;
 import net.minecraft.world.World;
 import net.minecraftforge.common.DimensionManager;
-import net.minecraftforge.fml.common.FMLCommonHandler;
-import net.minecraftforge.fml.common.Mod;
-import net.minecraftforge.fml.common.SidedProxy;
+import net.minecraftforge.fml.common.*;
 import net.minecraftforge.fml.common.event.*;
 import net.minecraftforge.fml.relauncher.Side;
 import org.apache.logging.log4j.Logger;
@@ -83,9 +81,7 @@ import java.io.*;
 import java.net.MalformedURLException;
 import java.net.URISyntaxException;
 import java.net.URL;
-import java.util.ArrayList;
-import java.util.EnumSet;
-import java.util.List;
+import java.util.*;
 import java.util.concurrent.TimeUnit;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;
@@ -394,6 +390,27 @@ public class ComputerCraft
         }
     }
 
+    private static void loadFromFile( List<IMount> mounts, File file, String path, boolean allowMissing )
+    {
+        try
+        {
+            if( file.isFile() )
+            {
+                mounts.add( new JarMount( file, path ) );
+            }
+            else
+            {
+                File subResource = new File( file, path );
+                if( subResource.exists() ) mounts.add( new FileMount( subResource, 0 ) );
+            }
+        }
+        catch( IOException | RuntimeException e )
+        {
+            if( allowMissing && e instanceof FileNotFoundException ) return;
+            ComputerCraft.log.error( "Could not load mount '" + path + " 'from '" + file.getName() + "'", e );
+        }
+    }
+
     @Deprecated
     public static IMount createResourceMount( Class<?> modClass, String domain, String subPath )
     {
@@ -413,18 +430,26 @@ public class ComputerCraft
             }
         }
 
-        // Mount from mod jar
+        // Mount from mod jars, preferring the specified one.
         File modJar = getContainingJar( modClass );
+        Set<File> otherMods = new HashSet<>();
+        for( ModContainer container : Loader.instance().getActiveModList() )
+        {
+            File modFile = container.getSource();
+            if( modFile != null && !modFile.equals( modJar ) && modFile.exists() )
+            {
+                otherMods.add( container.getSource() );
+            }
+        }
+
+        for( File file : otherMods )
+        {
+            loadFromFile( mounts, file, subPath, true );
+        }
+
         if( modJar != null )
         {
-            try
-            {
-                mounts.add( new JarMount( modJar, subPath ) );
-            }
-            catch( IOException | RuntimeException e )
-            {
-                ComputerCraft.log.error( "Could not load mount from mod jar", e );
-            }
+            loadFromFile( mounts, modJar, subPath, false );
         }
 
         // Mount from resource packs
@@ -434,28 +459,8 @@ public class ComputerCraft
             String[] resourcePacks = resourcePackDir.list();
             for( String resourcePackName : resourcePacks )
             {
-                try
-                {
-                    File resourcePack = new File( resourcePackDir, resourcePackName );
-                    if( !resourcePack.isDirectory() )
-                    {
-                        // Mount a resource pack from a jar
-                        mounts.add( new JarMount( resourcePack, subPath ) );
-                    }
-                    else
-                    {
-                        // Mount a resource pack from a folder
-                        File subResource = new File( resourcePack, subPath );
-                        if( subResource.exists() ) mounts.add( new FileMount( subResource, 0 ) );
-                    }
-                }
-                catch( FileNotFoundException ignored )
-                {
-                }
-                catch( IOException | RuntimeException e )
-                {
-                    ComputerCraft.log.error( "Could not load resource pack '" + resourcePackName + "'", e );
-                }
+                File resourcePack = new File( resourcePackDir, resourcePackName );
+                loadFromFile( mounts, resourcePack, subPath, true );
             }
         }
 

src/main/java/dan200/computercraft/api/ComputerCraftAPI.java

@@ -32,8 +32,9 @@ import java.lang.reflect.Method;
 
 /**
  * The static entry point to the ComputerCraft API.
- * Members in this class must be called after mod_ComputerCraft has been initialised,
- * but may be called before it is fully loaded.
+ *
+ * Members in this class must be called after mod_ComputerCraft has been initialised, but may be called before it is
+ * fully loaded.
  */
 public final class ComputerCraftAPI
 {
@@ -269,7 +270,7 @@ public final class ComputerCraftAPI
     }
 
     /**
-     * Registers a media provider to provide {@link IMedia} implementations for Items
+     * Registers a media provider to provide {@link IMedia} implementations for Items.
      *
      * @param provider The media provider to register.
      * @see IMediaProvider
@@ -370,7 +371,7 @@ public final class ComputerCraftAPI
     }
 
     /**
-     * Construct a new wired node for a given wired element
+     * Construct a new wired node for a given wired element.
      *
      * @param element The element to construct it for
      * @return The element's node
@@ -398,7 +399,7 @@ public final class ComputerCraftAPI
     }
 
     /**
-     * Get the wired network element for a block in world
+     * Get the wired network element for a block in world.
      *
      * @param world The world the block exists in
      * @param pos   The position the block exists in

src/main/java/dan200/computercraft/api/filesystem/IMount.java

@@ -19,7 +19,7 @@ import java.util.List;
 
 /**
  * Represents a read only part of a virtual filesystem that can be mounted onto a computer using
- * {@link IComputerAccess#mount(String, IMount)}
+ * {@link IComputerAccess#mount(String, IMount)}.
  *
  * Ready made implementations of this interface can be created using
  * {@link ComputerCraftAPI#createSaveDirMount(World, String, long)} or
@@ -60,7 +60,7 @@ public interface IMount
     void list( @Nonnull String path, @Nonnull List<String> contents ) throws IOException;
 
     /**
-     * Returns the size of a file with a given path, in bytes
+     * Returns the size of a file with a given path, in bytes.
      *
      * @param path A file path in normalised format, relative to the mount location. ie: "programs/myprogram".
      * @return The size of the file, in bytes.

src/main/java/dan200/computercraft/api/lua/ArgumentHelper.java

@@ -0,0 +1,335 @@
+/*
+ * This file is part of the public ComputerCraft API - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. This API may be redistributed unmodified and in full only.
+ * For help using the API, and posting your mods, visit the forums at computercraft.info.
+ */
+
+package dan200.computercraft.api.lua;
+
+import dan200.computercraft.api.peripheral.IComputerAccess;
+import dan200.computercraft.api.peripheral.IPeripheral;
+
+import javax.annotation.Nonnull;
+import javax.annotation.Nullable;
+import java.util.Map;
+
+/**
+ * Provides methods for extracting values and validating Lua arguments, such as those provided to
+ * {@link ILuaObject#callMethod(ILuaContext, int, Object[])} or
+ * {@link IPeripheral#callMethod(IComputerAccess, ILuaContext, int, Object[])}.
+ *
+ * This provides two sets of functions: the {@code get*} methods, which require an argument to be valid, and
+ * {@code opt*}, which accept a default value and return that if the argument was not present or was {@code null}.
+ * If the argument is of the wrong type, a suitable error message will be thrown, with a similar format to Lua's own
+ * error messages.
+ *
+ * <h2>Example usage:</h2>
+ * <pre>
+ * {@code
+ * int slot = getInt( args, 0 );
+ * int amount = optInt( args, 1, 64 );
+ * }
+ * </pre>
+ */
+public final class ArgumentHelper
+{
+    private ArgumentHelper()
+    {
+    }
+
+    /**
+     * Get a string representation of the given value's type.
+     *
+     * @param value The value whose type we are trying to compute.
+     * @return A string representation of the given value's type, in a similar format to that provided by Lua's
+     * {@code type} function.
+     */
+    @Nonnull
+    public static String getType( @Nullable Object value )
+    {
+        if( value == null ) return "nil";
+        if( value instanceof String ) return "string";
+        if( value instanceof Boolean ) return "boolean";
+        if( value instanceof Number ) return "number";
+        if( value instanceof Map ) return "table";
+        return "userdata";
+    }
+
+    /**
+     * Construct a "bad argument" exception, from an expected type and the actual value provided.
+     *
+     * @param index    The argument number, starting from 0.
+     * @param expected The expected type for this argument.
+     * @param actual   The actual value provided for this argument.
+     * @return The constructed exception, which should be thrown immediately.
+     */
+    @Nonnull
+    public static LuaException badArgumentOf( int index, @Nonnull String expected, @Nullable Object actual )
+    {
+        return badArgument( index, expected, getType( actual ) );
+    }
+
+    /**
+     * Construct a "bad argument" exception, from an expected and actual type.
+     *
+     * @param index    The argument number, starting from 0.
+     * @param expected The expected type for this argument.
+     * @param actual   The provided type for this argument.
+     * @return The constructed exception, which should be thrown immediately.
+     */
+    @Nonnull
+    public static LuaException badArgument( int index, @Nonnull String expected, @Nonnull String actual )
+    {
+        return new LuaException( "bad argument #" + (index + 1) + " (" + expected + " expected, got " + actual + ")" );
+    }
+
+    /**
+     * Get an argument as a double.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @return The argument's value.
+     * @throws LuaException If the value is not a number.
+     * @see #getFiniteDouble(Object[], int) if you require this to be finite (i.e. not infinite or NaN).
+     */
+    public static double getDouble( @Nonnull Object[] args, int index ) throws LuaException
+    {
+        if( index >= args.length ) throw badArgument( index, "number", "nil" );
+        Object value = args[index];
+        if( !(value instanceof Number) ) throw badArgumentOf( index, "number", value );
+        return ((Number) value).doubleValue();
+    }
+
+    /**
+     * Get an argument as an integer.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @return The argument's value.
+     * @throws LuaException If the value is not an integer.
+     */
+    public static int getInt( @Nonnull Object[] args, int index ) throws LuaException
+    {
+        return (int) getLong( args, index );
+    }
+
+    /**
+     * Get an argument as a long.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @return The argument's value.
+     * @throws LuaException If the value is not a long.
+     */
+    public static long getLong( @Nonnull Object[] args, int index ) throws LuaException
+    {
+        if( index >= args.length ) throw badArgument( index, "number", "nil" );
+        Object value = args[index];
+        if( !(value instanceof Number) ) throw badArgumentOf( index, "number", value );
+        return checkFinite( index, (Number) value ).longValue();
+    }
+
+    /**
+     * Get an argument as a finite number (not infinite or NaN).
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @return The argument's value.
+     * @throws LuaException If the value is not finite.
+     */
+    public static double getFiniteDouble( @Nonnull Object[] args, int index ) throws LuaException
+    {
+        return checkFinite( index, getDouble( args, index ) );
+    }
+
+    /**
+     * Get an argument as a boolean.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @return The argument's value.
+     * @throws LuaException If the value is not a boolean.
+     */
+    public static boolean getBoolean( @Nonnull Object[] args, int index ) throws LuaException
+    {
+        if( index >= args.length ) throw badArgument( index, "boolean", "nil" );
+        Object value = args[index];
+        if( !(value instanceof Boolean) ) throw badArgumentOf( index, "boolean", value );
+        return (Boolean) value;
+    }
+
+    /**
+     * Get an argument as a string.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @return The argument's value.
+     * @throws LuaException If the value is not a string.
+     */
+    @Nonnull
+    public static String getString( @Nonnull Object[] args, int index ) throws LuaException
+    {
+        if( index >= args.length ) throw badArgument( index, "string", "nil" );
+        Object value = args[index];
+        if( !(value instanceof String) ) throw badArgumentOf( index, "string", value );
+        return (String) value;
+    }
+
+    /**
+     * Get an argument as a table.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @return The argument's value.
+     * @throws LuaException If the value is not a table.
+     */
+    @Nonnull
+    public static Map<?, ?> getTable( @Nonnull Object[] args, int index ) throws LuaException
+    {
+        if( index >= args.length ) throw badArgument( index, "table", "nil" );
+        Object value = args[index];
+        if( !(value instanceof Map) ) throw badArgumentOf( index, "table", value );
+        return (Map<?, ?>) value;
+    }
+
+    /**
+     * Get an argument as a double.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @param def   The default value, if this argument is not given.
+     * @return The argument's value, or {@code def} if none was provided.
+     * @throws LuaException If the value is not a number.
+     */
+    public static double optDouble( @Nonnull Object[] args, int index, double def ) throws LuaException
+    {
+        Object value = index < args.length ? args[index] : null;
+        if( value == null ) return def;
+        if( !(value instanceof Number) ) throw badArgumentOf( index, "number", value );
+        return ((Number) value).doubleValue();
+    }
+
+    /**
+     * Get an argument as an int.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @param def   The default value, if this argument is not given.
+     * @return The argument's value, or {@code def} if none was provided.
+     * @throws LuaException If the value is not a number.
+     */
+    public static int optInt( @Nonnull Object[] args, int index, int def ) throws LuaException
+    {
+        return (int) optLong( args, index, def );
+    }
+
+    /**
+     * Get an argument as a long.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @param def   The default value, if this argument is not given.
+     * @return The argument's value, or {@code def} if none was provided.
+     * @throws LuaException If the value is not a number.
+     */
+    public static long optLong( @Nonnull Object[] args, int index, long def ) throws LuaException
+    {
+        Object value = index < args.length ? args[index] : null;
+        if( value == null ) return def;
+        if( !(value instanceof Number) ) throw badArgumentOf( index, "number", value );
+        return checkFinite( index, (Number) value ).longValue();
+    }
+
+    /**
+     * Get an argument as a finite number (not infinite or NaN).
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @param def   The default value, if this argument is not given.
+     * @return The argument's value, or {@code def} if none was provided.
+     * @throws LuaException If the value is not finite.
+     */
+    public static double optFiniteDouble( @Nonnull Object[] args, int index, double def ) throws LuaException
+    {
+        return checkFinite( index, optDouble( args, index, def ) );
+    }
+
+    /**
+     * Get an argument as a boolean.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @param def   The default value, if this argument is not given.
+     * @return The argument's value, or {@code def} if none was provided.
+     * @throws LuaException If the value is not a boolean.
+     */
+    public static boolean optBoolean( @Nonnull Object[] args, int index, boolean def ) throws LuaException
+    {
+        Object value = index < args.length ? args[index] : null;
+        if( value == null ) return def;
+        if( !(value instanceof Boolean) ) throw badArgumentOf( index, "boolean", value );
+        return (Boolean) value;
+    }
+
+    /**
+     * Get an argument as a string.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @param def   The default value, if this argument is not given.
+     * @return The argument's value, or {@code def} if none was provided.
+     * @throws LuaException If the value is not a string.
+     */
+    public static String optString( @Nonnull Object[] args, int index, String def ) throws LuaException
+    {
+        Object value = index < args.length ? args[index] : null;
+        if( value == null ) return def;
+        if( !(value instanceof String) ) throw badArgumentOf( index, "string", value );
+        return (String) value;
+    }
+
+    /**
+     * Get an argument as a table.
+     *
+     * @param args  The arguments to extract from.
+     * @param index The index into the argument array to read from.
+     * @param def   The default value, if this argument is not given.
+     * @return The argument's value, or {@code def} if none was provided.
+     * @throws LuaException If the value is not a table.
+     */
+    public static Map<?, ?> optTable( @Nonnull Object[] args, int index, Map<Object, Object> def ) throws LuaException
+    {
+        Object value = index < args.length ? args[index] : null;
+        if( value == null ) return def;
+        if( !(value instanceof Map) ) throw badArgumentOf( index, "table", value );
+        return (Map<?, ?>) value;
+    }
+
+    private static Number checkFinite( int index, Number value ) throws LuaException
+    {
+        checkFinite( index, value.doubleValue() );
+        return value;
+    }
+
+    private static double checkFinite( int index, double value ) throws LuaException
+    {
+        if( !Double.isFinite( value ) ) throw badArgument( index, "number", getNumericType( value ) );
+        return value;
+    }
+
+    /**
+     * Returns a more detailed representation of this number's type. If this is finite, it will just return "number",
+     * otherwise it returns whether it is infinite or NaN.
+     *
+     * @param value The value to extract the type for.
+     * @return This value's numeric type.
+     */
+    @Nonnull
+    public static String getNumericType( double value )
+    {
+        if( Double.isNaN( value ) ) return "nan";
+        if( value == Double.POSITIVE_INFINITY ) return "inf";
+        if( value == Double.NEGATIVE_INFINITY ) return "-inf";
+        return "number";
+    }
+}

src/main/java/dan200/computercraft/api/lua/IComputerSystem.java

@@ -26,7 +26,7 @@ public interface IComputerSystem extends IComputerAccess
     IFileSystem getFileSystem();
 
     /**
-     * Get the label for this computer
+     * Get the label for this computer.
      *
      * @return This computer's label, or {@code null} if it is not set.
      */

src/main/java/dan200/computercraft/api/peripheral/IPeripheral.java

@@ -6,6 +6,7 @@
 
 package dan200.computercraft.api.peripheral;
 
+import dan200.computercraft.api.lua.ArgumentHelper;
 import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.LuaException;
 
@@ -58,9 +59,11 @@ public interface IPeripheral
      *                  Lua values of type "table" will be represented by Object type Map.<br>
      *                  Lua values of any other type will be represented by a null object.<br>
      *                  This array will be empty if no arguments are passed.
+     *
+     *                  It is recommended you use {@link ArgumentHelper} in order to validate and process arguments.
      * @return An array of objects, representing values you wish to return to the lua program. Integers, Doubles, Floats,
-     * Strings, Booleans, Maps and ILuaObject and null be converted to their corresponding lua type. All other types
-     * will be converted to nil.
+     * Strings, Booleans, Maps, ILuaObject and null be converted to their corresponding lua type. All other types will
+     * be converted to nil.
      *
      * You may return null to indicate no values should be returned.
      * @throws LuaException         If you throw any exception from this function, a lua error will be raised with the
@@ -70,6 +73,7 @@ public interface IPeripheral
      *                              InterruptedException will be thrown. This exception must not be caught or
      *                              intercepted, or the computer will leak memory and end up in a broken state.
      * @see #getMethodNames
+     * @see ArgumentHelper
      */
     @Nullable
     Object[] callMethod( @Nonnull IComputerAccess computer, @Nonnull ILuaContext context, int method, @Nonnull Object[] arguments ) throws LuaException, InterruptedException;

src/main/java/dan200/computercraft/api/pocket/IPocketAccess.java

@@ -16,7 +16,7 @@ import javax.annotation.Nullable;
 import java.util.Map;
 
 /**
- * Wrapper class for pocket computers
+ * Wrapper class for pocket computers.
  */
 public interface IPocketAccess
 {

src/main/java/dan200/computercraft/api/turtle/ITurtleAccess.java

@@ -145,7 +145,9 @@ public interface ITurtleAccess
     GameProfile getOwningPlayer();
 
     /**
-     * Get the inventory of this turtle
+     * Get the inventory of this turtle.
+     *
+     * Note: this inventory should only be accessed and modified on the server thread.
      *
      * @return This turtle's inventory
      * @see #getItemHandler()
@@ -156,6 +158,8 @@ public interface ITurtleAccess
     /**
      * Get the inventory of this turtle as an {@link IItemHandlerModifiable}.
      *
+     * Note: this inventory should only be accessed and modified on the server thread.
+     *
      * @return This turtle's inventory
      * @see #getInventory()
      * @see IItemHandlerModifiable

src/main/java/dan200/computercraft/api/turtle/ITurtleUpgrade.java

@@ -109,8 +109,8 @@ public interface ITurtleUpgrade
      * Will only be called for Tool turtle. Called when turtle.dig() or turtle.attack() is called
      * by the turtle, and the tool is required to do some work.
      *
-     * Conforming implementations should fire {@link BlockEvent.BreakEvent} and {@link TurtleBlockEvent.Dig}for digging,
-     * {@link AttackEntityEvent} and {@link TurtleAttackEvent} for attacking.
+     * Conforming implementations should fire {@link BlockEvent.BreakEvent} and {@link TurtleBlockEvent.Dig} for
+     * digging, {@link AttackEntityEvent} and {@link TurtleAttackEvent} for attacking.
      *
      * @param turtle    Access to the turtle that the tool resides on.
      * @param side      Which side of the turtle (left or right) the tool resides on.

src/main/java/dan200/computercraft/api/turtle/TurtleSide.java

@@ -12,12 +12,12 @@ package dan200.computercraft.api.turtle;
 public enum TurtleSide
 {
     /**
-     * The turtle's left side (where the pickaxe usually is on a Wireless Mining Turtle)
+     * The turtle's left side (where the pickaxe usually is on a Wireless Mining Turtle).
      */
     Left,
 
     /**
-     * The turtle's right side (where the modem usually is on a Wireless Mining Turtle)
+     * The turtle's right side (where the modem usually is on a Wireless Mining Turtle).
      */
     Right,
 }

src/main/java/dan200/computercraft/api/turtle/TurtleVerb.java

@@ -18,12 +18,12 @@ import net.minecraft.util.EnumFacing;
 public enum TurtleVerb
 {
     /**
-     * The turtle called {@code turtle.dig()}, {@code turtle.digUp()} or {@code turtle.digDown()}
+     * The turtle called {@code turtle.dig()}, {@code turtle.digUp()} or {@code turtle.digDown()}.
      */
     Dig,
 
     /**
-     * The turtle called {@code turtle.attack()}, {@code turtle.attackUp()} or {@code turtle.attackDown()}
+     * The turtle called {@code turtle.attack()}, {@code turtle.attackUp()} or {@code turtle.attackDown()}.
      */
     Attack,
 }

src/main/java/dan200/computercraft/api/turtle/event/TurtleAction.java

@@ -71,7 +71,7 @@ public enum TurtleAction
     EQUIP,
 
     /**
-     * Inspect a block in world
+     * Inspect a block in world.
      *
      * @see TurtleBlockEvent.Inspect
      */

src/main/java/dan200/computercraft/api/turtle/event/TurtleBlockEvent.java

@@ -112,7 +112,7 @@ public abstract class TurtleBlockEvent extends TurtlePlayerEvent
         }
 
         /**
-         * Get the upgrade doing the digging
+         * Get the upgrade doing the digging.
          *
          * @return The upgrade doing the digging.
          */

src/main/java/dan200/computercraft/api/turtle/event/TurtleInventoryEvent.java

@@ -31,7 +31,7 @@ public abstract class TurtleInventoryEvent extends TurtleBlockEvent
     }
 
     /**
-     * Get the inventory being interacted with
+     * Get the inventory being interacted with.
      *
      * @return The inventory being interacted with, {@code null} if the item will be dropped to/sucked from the world.
      */

src/main/java/dan200/computercraft/client/render/ItemMapLikeRenderer.java

@@ -18,7 +18,7 @@ import net.minecraft.util.math.MathHelper;
 public abstract class ItemMapLikeRenderer
 {
     /**
-     * The main rendering method for the item
+     * The main rendering method for the item.
      *
      * @param stack The stack to render
      * @see ItemRenderer#renderMapFirstPerson(ItemStack)
@@ -87,7 +87,7 @@ public abstract class ItemMapLikeRenderer
     }
 
     /**
-     * Render an item in the middle of the screen
+     * Render an item in the middle of the screen.
      *
      * @param pitch         The pitch of the player
      * @param equipProgress The equip progress of this item

src/main/java/dan200/computercraft/client/render/ItemPocketRenderer.java

@@ -32,7 +32,7 @@ import static dan200.computercraft.client.gui.FixedWidthFontRenderer.*;
 import static dan200.computercraft.client.gui.GuiComputer.*;
 
 /**
- * Emulates map rendering for pocket computers
+ * Emulates map rendering for pocket computers.
  */
 @Mod.EventBusSubscriber( modid = ComputerCraft.MOD_ID, value = Side.CLIENT )
 public final class ItemPocketRenderer extends ItemMapLikeRenderer

src/main/java/dan200/computercraft/client/render/ItemPrintoutRenderer.java

@@ -23,7 +23,7 @@ import static dan200.computercraft.shared.media.items.ItemPrintout.LINES_PER_PAG
 import static dan200.computercraft.shared.media.items.ItemPrintout.LINE_MAX_LENGTH;
 
 /**
- * Emulates map and item-frame rendering for printouts
+ * Emulates map and item-frame rendering for printouts.
  */
 @Mod.EventBusSubscriber( modid = ComputerCraft.MOD_ID, value = Side.CLIENT )
 public final class ItemPrintoutRenderer extends ItemMapLikeRenderer

src/main/java/dan200/computercraft/client/render/PrintoutRenderer.java

@@ -28,32 +28,32 @@ public final class PrintoutRenderer
     private static final double BG_SIZE = 256.0;
 
     /**
-     * Width of a page
+     * Width of a page.
      */
     public static final int X_SIZE = 172;
 
     /**
-     * Height of a page
+     * Height of a page.
      */
     public static final int Y_SIZE = 209;
 
     /**
-     * Padding between the left and right of a page and the text
+     * Padding between the left and right of a page and the text.
      */
     public static final int X_TEXT_MARGIN = 13;
 
     /**
-     * Padding between the top and bottom of a page and the text
+     * Padding between the top and bottom of a page and the text.
      */
     public static final int Y_TEXT_MARGIN = 11;
 
     /**
-     * Width of the extra page texture
+     * Width of the extra page texture.
      */
     private static final int X_FOLD_SIZE = 12;
 
     /**
-     * Size of the leather cover
+     * Size of the leather cover.
      */
     public static final int COVER_SIZE = 12;
 

src/main/java/dan200/computercraft/client/render/TileEntityCableRenderer.java

@@ -97,6 +97,8 @@ public class TileEntityCableRenderer extends TileEntitySpecialRenderer<TileCable
     }
 
     /**
+     * Set up the state for rendering block-breaking progress.
+     *
      * @see RenderGlobal#preRenderDamagedBlocks()
      */
     private void preRenderDamagedBlocks()
@@ -115,6 +117,8 @@ public class TileEntityCableRenderer extends TileEntitySpecialRenderer<TileCable
     }
 
     /**
+     * Tear down the state for rendering block-breaking progress.
+     *
      * @see RenderGlobal#postRenderDamagedBlocks()
      */
     private void postRenderDamagedBlocks()

src/main/java/dan200/computercraft/core/apis/AddressPredicate.java

@@ -154,7 +154,7 @@ public class AddressPredicate
     }
 
     /**
-     * Determine whether the given address matches a series of patterns
+     * Determine whether the given address matches a series of patterns.
      *
      * @param address The address to check.
      * @return Whether it matches any of these patterns.

src/main/java/dan200/computercraft/core/apis/ArgumentHelper.java

@@ -13,256 +13,106 @@ import javax.annotation.Nullable;
 import java.util.Map;
 
 /**
- * Various helpers for arguments
+ * A stub for any mods which depended on this version of the argument helper.
+ *
+ * @deprecated Use {@link dan200.computercraft.api.lua.ArgumentHelper}.
  */
+@Deprecated
 public final class ArgumentHelper
 {
     private ArgumentHelper()
     {
-        throw new IllegalStateException( "Cannot instantiate singleton " + getClass().getName() );
     }
 
     @Nonnull
     public static String getType( @Nullable Object type )
     {
-        if( type == null ) return "nil";
-        if( type instanceof String ) return "string";
-        if( type instanceof Boolean ) return "boolean";
-        if( type instanceof Number ) return "number";
-        if( type instanceof Map ) return "table";
-
-        Class<?> klass = type.getClass();
-        if( klass.isArray() )
-        {
-            StringBuilder name = new StringBuilder();
-            while( klass.isArray() )
-            {
-                name.append( "[]" );
-                klass = klass.getComponentType();
-            }
-            name.insert( 0, klass.getName() );
-            return name.toString();
-        }
-        else
-        {
-            return klass.getName();
-        }
+        return dan200.computercraft.api.lua.ArgumentHelper.getType( type );
     }
 
     @Nonnull
     public static LuaException badArgument( int index, @Nonnull String expected, @Nullable Object actual )
     {
-        return badArgument( index, expected, getType( actual ) );
+        return dan200.computercraft.api.lua.ArgumentHelper.badArgumentOf( index, expected, actual );
     }
 
     @Nonnull
     public static LuaException badArgument( int index, @Nonnull String expected, @Nonnull String actual )
     {
-        return new LuaException( "bad argument #" + (index + 1) + " (" + expected + " expected, got " + actual + ")" );
+        return dan200.computercraft.api.lua.ArgumentHelper.badArgument( index, expected, actual );
     }
 
     public static double getNumber( @Nonnull Object[] args, int index ) throws LuaException
     {
-        if( index >= args.length ) throw badArgument( index, "number", "nil" );
-        Object value = args[index];
-        if( value instanceof Number )
-        {
-            return ((Number) value).doubleValue();
-        }
-        else
-        {
-            throw badArgument( index, "number", value );
-        }
+        return dan200.computercraft.api.lua.ArgumentHelper.getDouble( args, index );
     }
 
     public static int getInt( @Nonnull Object[] args, int index ) throws LuaException
     {
-        return (int) getLong( args, index );
+        return dan200.computercraft.api.lua.ArgumentHelper.getInt( args, index );
     }
 
     public static long getLong( @Nonnull Object[] args, int index ) throws LuaException
     {
-        if( index >= args.length ) throw badArgument( index, "number", "nil" );
-        Object value = args[index];
-        if( value instanceof Number )
-        {
-            return checkReal( index, (Number) value ).longValue();
-        }
-        else
-        {
-            throw badArgument( index, "number", value );
-        }
+        return dan200.computercraft.api.lua.ArgumentHelper.getLong( args, index );
     }
 
     public static double getReal( @Nonnull Object[] args, int index ) throws LuaException
     {
-        return checkReal( index, getNumber( args, index ) );
+        return dan200.computercraft.api.lua.ArgumentHelper.getFiniteDouble( args, index );
     }
 
     public static boolean getBoolean( @Nonnull Object[] args, int index ) throws LuaException
     {
-        if( index >= args.length ) throw badArgument( index, "boolean", "nil" );
-        Object value = args[index];
-        if( value instanceof Boolean )
-        {
-            return (Boolean) value;
-        }
-        else
-        {
-            throw badArgument( index, "boolean", value );
-        }
+        return dan200.computercraft.api.lua.ArgumentHelper.getBoolean( args, index );
     }
 
     @Nonnull
     public static String getString( @Nonnull Object[] args, int index ) throws LuaException
     {
-        if( index >= args.length ) throw badArgument( index, "string", "nil" );
-        Object value = args[index];
-        if( value instanceof String )
-        {
-            return (String) value;
-        }
-        else
-        {
-            throw badArgument( index, "string", value );
-        }
+        return dan200.computercraft.api.lua.ArgumentHelper.getString( args, index );
     }
 
-    @SuppressWarnings( "unchecked" )
     @Nonnull
+    @SuppressWarnings( "unchecked" )
     public static Map<Object, Object> getTable( @Nonnull Object[] args, int index ) throws LuaException
     {
-        if( index >= args.length ) throw badArgument( index, "table", "nil" );
-        Object value = args[index];
-        if( value instanceof Map )
-        {
-            return (Map<Object, Object>) value;
-        }
-        else
-        {
-            throw badArgument( index, "table", value );
-        }
+        return (Map<Object, Object>) dan200.computercraft.api.lua.ArgumentHelper.getTable( args, index );
     }
 
     public static double optNumber( @Nonnull Object[] args, int index, double def ) throws LuaException
     {
-        Object value = index < args.length ? args[index] : null;
-        if( value == null )
-        {
-            return def;
-        }
-        else if( value instanceof Number )
-        {
-            return ((Number) value).doubleValue();
-        }
-        else
-        {
-            throw badArgument( index, "number", value );
-        }
+        return dan200.computercraft.api.lua.ArgumentHelper.optDouble( args, index, def );
     }
 
     public static int optInt( @Nonnull Object[] args, int index, int def ) throws LuaException
     {
-        return (int) optLong( args, index, def );
+        return dan200.computercraft.api.lua.ArgumentHelper.optInt( args, index, def );
     }
 
     public static long optLong( @Nonnull Object[] args, int index, long def ) throws LuaException
     {
-        Object value = index < args.length ? args[index] : null;
-        if( value == null )
-        {
-            return def;
-        }
-        else if( value instanceof Number )
-        {
-            return checkReal( index, (Number) value ).longValue();
-        }
-        else
-        {
-            throw badArgument( index, "number", value );
-        }
+        return dan200.computercraft.api.lua.ArgumentHelper.optLong( args, index, def );
     }
 
     public static double optReal( @Nonnull Object[] args, int index, double def ) throws LuaException
     {
-        return checkReal( index, optNumber( args, index, def ) );
+        return dan200.computercraft.api.lua.ArgumentHelper.optFiniteDouble( args, index, def );
     }
 
     public static boolean optBoolean( @Nonnull Object[] args, int index, boolean def ) throws LuaException
     {
-        Object value = index < args.length ? args[index] : null;
-        if( value == null )
-        {
-            return def;
-        }
-        else if( value instanceof Boolean )
-        {
-            return (Boolean) value;
-        }
-        else
-        {
-            throw badArgument( index, "boolean", value );
-        }
+        return dan200.computercraft.api.lua.ArgumentHelper.optBoolean( args, index, def );
     }
 
     public static String optString( @Nonnull Object[] args, int index, String def ) throws LuaException
     {
-        Object value = index < args.length ? args[index] : null;
-        if( value == null )
-        {
-            return def;
-        }
-        else if( value instanceof String )
-        {
-            return (String) value;
-        }
-        else
-        {
-            throw badArgument( index, "string", value );
-        }
+        return dan200.computercraft.api.lua.ArgumentHelper.optString( args, index, def );
     }
 
     @SuppressWarnings( "unchecked" )
     public static Map<Object, Object> optTable( @Nonnull Object[] args, int index, Map<Object, Object> def ) throws LuaException
     {
-        Object value = index < args.length ? args[index] : null;
-        if( value == null )
-        {
-            return def;
-        }
-        else if( value instanceof Map )
-        {
-            return (Map<Object, Object>) value;
-        }
-        else
-        {
-            throw badArgument( index, "table", value );
-        }
-    }
-
-    private static Number checkReal( int index, Number value ) throws LuaException
-    {
-        checkReal( index, value.doubleValue() );
-        return value;
-    }
-
-    private static double checkReal( int index, double value ) throws LuaException
-    {
-        if( Double.isNaN( value ) )
-        {
-            throw badArgument( index, "number", "nan" );
-        }
-        else if( value == Double.POSITIVE_INFINITY )
-        {
-            throw badArgument( index, "number", "inf" );
-        }
-        else if( value == Double.NEGATIVE_INFINITY )
-        {
-            throw badArgument( index, "number", "-inf" );
-        }
-        else
-        {
-            return value;
-        }
+        return (Map<Object, Object>) dan200.computercraft.api.lua.ArgumentHelper.optTable( args, index, def );
     }
 }

src/main/java/dan200/computercraft/core/apis/FSAPI.java

@@ -27,7 +27,7 @@ import java.util.HashMap;
 import java.util.Map;
 import java.util.function.Function;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.getString;
+import static dan200.computercraft.api.lua.ArgumentHelper.getString;
 
 public class FSAPI implements ILuaAPI
 {

src/main/java/dan200/computercraft/core/apis/HTTPAPI.java

@@ -23,7 +23,7 @@ import java.util.Collections;
 import java.util.Locale;
 import java.util.Map;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.*;
+import static dan200.computercraft.api.lua.ArgumentHelper.*;
 import static dan200.computercraft.core.apis.TableHelper.*;
 
 public class HTTPAPI implements ILuaAPI
@@ -89,7 +89,7 @@ public class HTTPAPI implements ILuaAPI
             case 0: // request
             {
                 String address, postString, requestMethod;
-                Map<Object, Object> headerTable;
+                Map<?, ?> headerTable;
                 boolean binary, redirect;
 
                 if( args.length >= 1 && args[0] instanceof Map )
@@ -172,7 +172,7 @@ public class HTTPAPI implements ILuaAPI
             case 2: // websocket
             {
                 String address = getString( args, 0 );
-                Map<Object, Object> headerTbl = optTable( args, 1, Collections.emptyMap() );
+                Map<?, ?> headerTbl = optTable( args, 1, Collections.emptyMap() );
 
                 if( !ComputerCraft.http_websocket_enable )
                 {

src/main/java/dan200/computercraft/core/apis/OSAPI.java

@@ -19,7 +19,7 @@ import java.time.ZonedDateTime;
 import java.time.format.DateTimeFormatterBuilder;
 import java.util.*;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.*;
+import static dan200.computercraft.api.lua.ArgumentHelper.*;
 
 public class OSAPI implements ILuaAPI
 {
@@ -229,7 +229,7 @@ public class OSAPI implements ILuaAPI
             case 1:
             {
                 // startTimer
-                double timer = getReal( args, 0 );
+                double timer = getFiniteDouble( args, 0 );
                 synchronized( m_timers )
                 {
                     m_timers.put( m_nextTimerToken, new Timer( (int) Math.round( timer / 0.05 ) ) );
@@ -239,7 +239,7 @@ public class OSAPI implements ILuaAPI
             case 2:
             {
                 // setAlarm
-                double time = getReal( args, 0 );
+                double time = getFiniteDouble( args, 0 );
                 if( time < 0.0 || time >= 24.0 )
                 {
                     throw new LuaException( "Number out of range" );

src/main/java/dan200/computercraft/core/apis/PeripheralAPI.java

@@ -22,7 +22,7 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.getString;
+import static dan200.computercraft.api.lua.ArgumentHelper.getString;
 
 public class PeripheralAPI implements ILuaAPI, IAPIEnvironment.IPeripheralChangeListener
 {

src/main/java/dan200/computercraft/core/apis/RedstoneAPI.java

@@ -15,7 +15,7 @@ import javax.annotation.Nonnull;
 import java.util.HashMap;
 import java.util.Map;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.*;
+import static dan200.computercraft.api.lua.ArgumentHelper.*;
 
 public class RedstoneAPI implements ILuaAPI
 {

src/main/java/dan200/computercraft/core/apis/TableHelper.java

@@ -6,14 +6,17 @@
 
 package dan200.computercraft.core.apis;
 
+import dan200.computercraft.api.lua.ArgumentHelper;
 import dan200.computercraft.api.lua.LuaException;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.util.Map;
 
+import static dan200.computercraft.api.lua.ArgumentHelper.getNumericType;
+
 /**
- * Various helpers for tables
+ * Various helpers for tables.
  */
 public final class TableHelper
 {
@@ -200,21 +203,7 @@ public final class TableHelper
 
     private static double checkReal( @Nonnull String key, double value ) throws LuaException
     {
-        if( Double.isNaN( value ) )
-        {
-            throw badKey( key, "number", "nan" );
-        }
-        else if( value == Double.POSITIVE_INFINITY )
-        {
-            throw badKey( key, "number", "inf" );
-        }
-        else if( value == Double.NEGATIVE_INFINITY )
-        {
-            throw badKey( key, "number", "-inf" );
-        }
-        else
-        {
-            return value;
-        }
+        if( !Double.isFinite( value ) ) throw badKey( key, "number", getNumericType( value ) );
+        return value;
     }
 }

src/main/java/dan200/computercraft/core/apis/TermAPI.java

@@ -17,7 +17,7 @@ import org.apache.commons.lang3.ArrayUtils;
 
 import javax.annotation.Nonnull;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.*;
+import static dan200.computercraft.api.lua.ArgumentHelper.*;
 
 public class TermAPI implements ILuaAPI
 {
@@ -242,9 +242,9 @@ public class TermAPI implements ILuaAPI
                 }
                 else
                 {
-                    double r = getReal( args, 1 );
-                    double g = getReal( args, 2 );
-                    double b = getReal( args, 3 );
+                    double r = getFiniteDouble( args, 1 );
+                    double g = getFiniteDouble( args, 2 );
+                    double b = getFiniteDouble( args, 3 );
                     setColour( m_terminal, colour, r, g, b );
                 }
                 return null;

src/main/java/dan200/computercraft/core/apis/handles/BinaryReadableHandle.java

@@ -21,8 +21,8 @@ import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.getInt;
-import static dan200.computercraft.core.apis.ArgumentHelper.optBoolean;
+import static dan200.computercraft.api.lua.ArgumentHelper.getInt;
+import static dan200.computercraft.api.lua.ArgumentHelper.optBoolean;
 
 public class BinaryReadableHandle extends HandleGeneric
 {

src/main/java/dan200/computercraft/core/apis/handles/BinaryWritableHandle.java

@@ -7,9 +7,9 @@
 package dan200.computercraft.core.apis.handles;
 
 import com.google.common.collect.ObjectArrays;
+import dan200.computercraft.api.lua.ArgumentHelper;
 import dan200.computercraft.api.lua.ILuaContext;
 import dan200.computercraft.api.lua.LuaException;
-import dan200.computercraft.core.apis.ArgumentHelper;
 import dan200.computercraft.shared.util.StringUtil;
 
 import javax.annotation.Nonnull;
@@ -73,7 +73,7 @@ public class BinaryWritableHandle extends HandleGeneric
                     }
                     else
                     {
-                        throw ArgumentHelper.badArgument( 0, "string or number", args.length > 0 ? args[0] : null );
+                        throw ArgumentHelper.badArgumentOf( 0, "string or number", args.length > 0 ? args[0] : null );
                     }
                     return null;
                 }

src/main/java/dan200/computercraft/core/apis/handles/EncodedReadableHandle.java

@@ -20,8 +20,8 @@ import java.nio.charset.CharsetDecoder;
 import java.nio.charset.CodingErrorAction;
 import java.nio.charset.StandardCharsets;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.optBoolean;
-import static dan200.computercraft.core.apis.ArgumentHelper.optInt;
+import static dan200.computercraft.api.lua.ArgumentHelper.optBoolean;
+import static dan200.computercraft.api.lua.ArgumentHelper.optInt;
 
 public class EncodedReadableHandle extends HandleGeneric
 {

src/main/java/dan200/computercraft/core/apis/handles/HandleGeneric.java

@@ -16,8 +16,8 @@ import java.io.IOException;
 import java.nio.channels.Channel;
 import java.nio.channels.SeekableByteChannel;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.optLong;
-import static dan200.computercraft.core.apis.ArgumentHelper.optString;
+import static dan200.computercraft.api.lua.ArgumentHelper.optLong;
+import static dan200.computercraft.api.lua.ArgumentHelper.optString;
 
 public abstract class HandleGeneric implements ILuaObject
 {
@@ -47,7 +47,7 @@ public abstract class HandleGeneric implements ILuaObject
     }
 
     /**
-     * Shared implementation for various file handle types
+     * Shared implementation for various file handle types.
      *
      * @param channel The channel to seek in
      * @param args    The Lua arguments to process, like Lua's {@code file:seek}.

src/main/java/dan200/computercraft/core/apis/http/NetworkUtils.java

@@ -99,7 +99,7 @@ public final class NetworkUtils
     }
 
     /**
-     * Checks a host is allowed
+     * Checks a host is allowed.
      *
      * @param host The domain to check against
      * @throws HTTPRequestException If the host is not permitted.

src/main/java/dan200/computercraft/core/apis/http/Resource.java

@@ -20,6 +20,8 @@ import java.util.function.Consumer;
 
 /**
  * A holder for one or more resources, with a lifetime.
+ *
+ * @param <T> The type of this resource. Should be the class extending from {@link Resource}.
  */
 public abstract class Resource<T extends Resource<T>> implements Closeable
 {
@@ -42,8 +44,9 @@ public abstract class Resource<T extends Resource<T>> implements Closeable
     }
 
     /**
-     * Checks if this has been cancelled. If so, it'll clean up any
-     * existing resources and cancel any pending futures.
+     * Checks if this has been cancelled. If so, it'll clean up any existing resources and cancel any pending futures.
+     *
+     * @return Whether this resource has been closed.
      */
     public final boolean checkClosed()
     {
@@ -80,6 +83,7 @@ public abstract class Resource<T extends Resource<T>> implements Closeable
     /**
      * Create a {@link WeakReference} which will close {@code this} when collected.
      *
+     * @param <R>    The object we are wrapping in a reference.
      * @param object The object to reference to
      * @return The weak reference.
      */

src/main/java/dan200/computercraft/core/apis/http/ResourceGroup.java

@@ -14,6 +14,8 @@ import java.util.function.Supplier;
 
 /**
  * A collection of {@link Resource}s, with an upper bound on capacity.
+ *
+ * @param <T> The type of the resource this group manages.
  */
 public class ResourceGroup<T extends Resource<T>>
 {

src/main/java/dan200/computercraft/core/apis/http/ResourceQueue.java

@@ -12,6 +12,8 @@ import java.util.function.Supplier;
 
 /**
  * A {@link ResourceGroup} which will queue items when the group at capacity.
+ *
+ * @param <T> The type of the resource this queue manages.
  */
 public class ResourceQueue<T extends Resource<T>> extends ResourceGroup<T>
 {

src/main/java/dan200/computercraft/core/apis/http/request/HttpRequest.java

@@ -40,7 +40,7 @@ import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
 
 /**
- * Represents one or more
+ * Represents an in-progress HTTP request.
  */
 public class HttpRequest extends Resource<HttpRequest>
 {

src/main/java/dan200/computercraft/core/apis/http/request/HttpRequestHandler.java

@@ -226,7 +226,11 @@ public final class HttpRequestHandler extends SimpleChannelInboundHandler<HttpOb
     }
 
     /**
-     * Determine the redirect from this response
+     * Determine the redirect from this response.
+     *
+     * @param status  The status of the HTTP response.
+     * @param headers The headers of the HTTP response.
+     * @return The URI to redirect to, or {@code null} if no redirect should occur.
      */
     private URI getRedirect( HttpResponseStatus status, HttpHeaders headers )
     {

src/main/java/dan200/computercraft/core/apis/http/websocket/WebsocketHandle.java

@@ -23,7 +23,7 @@ import javax.annotation.Nullable;
 import java.io.Closeable;
 import java.util.Arrays;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.optBoolean;
+import static dan200.computercraft.api.lua.ArgumentHelper.optBoolean;
 import static dan200.computercraft.core.apis.http.websocket.Websocket.CLOSE_EVENT;
 import static dan200.computercraft.core.apis.http.websocket.Websocket.MESSAGE_EVENT;
 

src/main/java/dan200/computercraft/core/computer/ComputerExecutor.java

@@ -268,7 +268,7 @@ final class ComputerExecutor
     }
 
     /**
-     * Queue an event if the computer is on
+     * Queue an event if the computer is on.
      *
      * @param event The event's name
      * @param args  The event's arguments

src/main/java/dan200/computercraft/core/computer/ComputerThread.java

@@ -50,7 +50,7 @@ import static dan200.computercraft.core.computer.TimeoutState.TIMEOUT;
 public final class ComputerThread
 {
     /**
-     * How often the computer thread monitor should run, in milliseconds
+     * How often the computer thread monitor should run, in milliseconds.
      *
      * @see Monitor
      */
@@ -83,7 +83,7 @@ public final class ComputerThread
     private static final Object threadLock = new Object();
 
     /**
-     * Whether the computer thread system is currently running
+     * Whether the computer thread system is currently running.
      */
     private static volatile boolean running = false;
 
@@ -105,7 +105,7 @@ public final class ComputerThread
     private static final Condition hasWork = computerLock.newCondition();
 
     /**
-     * Active queues to execute
+     * Active queues to execute.
      */
     private static final TreeSet<ComputerExecutor> computerQueue = new TreeSet<>( ( a, b ) -> {
         if( a == b ) return 0; // Should never happen, but let's be consistent here
@@ -126,7 +126,7 @@ public final class ComputerThread
     private ComputerThread() {}
 
     /**
-     * Start the computer thread
+     * Start the computer thread.
      */
     static void start()
     {
@@ -194,7 +194,7 @@ public final class ComputerThread
     }
 
     /**
-     * Mark a computer as having work, enqueuing it on the thread
+     * Mark a computer as having work, enqueuing it on the thread.
      *
      * You must be holding {@link ComputerExecutor}'s {@code queueLock} when calling this method - it should only
      * be called from {@code enqueue}.
@@ -244,6 +244,8 @@ public final class ComputerThread
      * {@link #minimumVirtualRuntime} based on the current tasks.
      *
      * This is called before queueing tasks, to ensure that {@link #minimumVirtualRuntime} is up-to-date.
+     *
+     * @param current The machine which we updating runtimes from.
      */
     private static void updateRuntimes( @Nullable ComputerExecutor current )
     {
@@ -321,7 +323,7 @@ public final class ComputerThread
     }
 
     /**
-     * The scaled period for a single task
+     * The scaled period for a single task.
      *
      * @return The scaled period for the task
      * @see #DEFAULT_LATENCY
@@ -336,7 +338,7 @@ public final class ComputerThread
     }
 
     /**
-     * Determine if the thread has computers queued up
+     * Determine if the thread has computers queued up.
      *
      * @return If we have work queued up.
      */

src/main/java/dan200/computercraft/core/computer/TimeoutState.java

@@ -36,12 +36,12 @@ import java.util.concurrent.TimeUnit;
 public final class TimeoutState
 {
     /**
-     * The total time a task is allowed to run before aborting in nanoseconds
+     * The total time a task is allowed to run before aborting in nanoseconds.
      */
     static final long TIMEOUT = TimeUnit.MILLISECONDS.toNanos( 7000 );
 
     /**
-     * The time the task is allowed to run after each abort in nanoseconds
+     * The time the task is allowed to run after each abort in nanoseconds.
      */
     static final long ABORT_TIMEOUT = TimeUnit.MILLISECONDS.toNanos( 1500 );
 
@@ -111,6 +111,8 @@ public final class TimeoutState
 
     /**
      * If the machine should be passively aborted.
+     *
+     * @return {@code true} if we should throw a timeout error.
      */
     public boolean isSoftAborted()
     {
@@ -118,7 +120,9 @@ public final class TimeoutState
     }
 
     /**
-     * If the machine should be forcibly aborted.
+     * Determine if the machine should be forcibly aborted.
+     *
+     * @return {@code true} if the machine should be forcibly shut down.
      */
     public boolean isHardAborted()
     {
@@ -146,7 +150,7 @@ public final class TimeoutState
     }
 
     /**
-     * Pauses the cumulative time, to be resumed by {@link #startTimer()}
+     * Pauses the cumulative time, to be resumed by {@link #startTimer()}.
      *
      * @see #nanoCumulative()
      */

src/main/java/dan200/computercraft/core/lua/MachineResult.java

@@ -38,7 +38,7 @@ public final class MachineResult
     public static final MachineResult TIMEOUT = new MachineResult( true, false, TimeoutState.ABORT_MESSAGE );
 
     /**
-     * An error with no user-friendly error message
+     * An error with no user-friendly error message.
      */
     public static final MachineResult GENERIC_ERROR = new MachineResult( true, false, null );
 

src/main/java/dan200/computercraft/core/terminal/Terminal.java

@@ -314,6 +314,9 @@ public class Terminal
     }
 
     /**
+     * Determine whether this terminal has changed.
+     *
+     * @return If this terminal is dirty.
      * @deprecated All {@code *Changed()} methods are deprecated: one should pass in a callback
      * instead.
      */

src/main/java/dan200/computercraft/shared/Config.java

@@ -54,8 +54,8 @@ public final class Config
 
     private static Property httpEnable;
     private static Property httpWebsocketEnable;
-    private static Property httpWhitelist;
-    private static Property httpBlacklist;
+    private static Property httpAllowedDomains;
+    private static Property httpBlockedDomains;
 
     private static Property httpTimeout;
     private static Property httpMaxRequests;
@@ -163,30 +163,32 @@ public final class Config
         { // HTTP
             renameProperty( CATEGORY_GENERAL, "http_enable", CATEGORY_HTTP, "enabled" );
             renameProperty( CATEGORY_GENERAL, "http_websocket_enable", CATEGORY_HTTP, "websocket_enabled" );
-            renameProperty( CATEGORY_GENERAL, "http_whitelist", CATEGORY_HTTP, "whitelist" );
-            renameProperty( CATEGORY_GENERAL, "http_blacklist", CATEGORY_HTTP, "blacklist" );
+            renameProperty( CATEGORY_GENERAL, "http_whitelist", CATEGORY_HTTP, "allowed_domains" );
+            renameProperty( CATEGORY_GENERAL, "http_blacklist", CATEGORY_HTTP, "blocked_domains" );
+            renameProperty( CATEGORY_HTTP, "whitelist", CATEGORY_HTTP, "allowed_domains" );
+            renameProperty( CATEGORY_HTTP, "blacklist", CATEGORY_HTTP, "blocked_domains" );
 
             config.getCategory( CATEGORY_HTTP )
                 .setComment( "Controls the HTTP API" );
 
             httpEnable = config.get( CATEGORY_HTTP, "enabled", ComputerCraft.http_enable );
-            httpEnable.setComment( "Enable the \"http\" API on Computers (see \"http_whitelist\" and \"http_blacklist\" for " +
-                "more fine grained control than this)" );
+            httpEnable.setComment( "Enable the \"http\" API on Computers (see \"allowed_domains\" and \"blocked_domains\" " +
+                "for more fine grained control than this)" );
 
             httpWebsocketEnable = config.get( CATEGORY_HTTP, "websocket_enabled", ComputerCraft.http_websocket_enable );
             httpWebsocketEnable.setComment( "Enable use of http websockets. This requires the \"http_enable\" option to also be true." );
 
-            httpWhitelist = config.get( CATEGORY_HTTP, "whitelist", DEFAULT_HTTP_WHITELIST );
-            httpWhitelist.setComment( "A list of wildcards for domains or IP ranges that can be accessed through the " +
+            httpAllowedDomains = config.get( CATEGORY_HTTP, "allowed_domains", DEFAULT_HTTP_WHITELIST );
+            httpAllowedDomains.setComment( "A list of wildcards for domains or IP ranges that can be accessed through the " +
                 "\"http\" API on Computers.\n" +
                 "Set this to \"*\" to access to the entire internet. Example: \"*.pastebin.com\" will restrict access to " +
                 "just subdomains of pastebin.com.\n" +
                 "You can use domain names (\"pastebin.com\"), wilcards (\"*.pastebin.com\") or CIDR notation (\"127.0.0.0/8\")." );
 
-            httpBlacklist = config.get( CATEGORY_HTTP, "blacklist", DEFAULT_HTTP_BLACKLIST );
-            httpBlacklist.setComment( "A list of wildcards for domains or IP ranges that cannot be accessed through the " +
+            httpBlockedDomains = config.get( CATEGORY_HTTP, "blocked_domains", DEFAULT_HTTP_BLACKLIST );
+            httpBlockedDomains.setComment( "A list of wildcards for domains or IP ranges that cannot be accessed through the " +
                 "\"http\" API on Computers.\n" +
-                "If this is empty then all whitelisted domains will be accessible. Example: \"*.github.com\" will block " +
+                "If this is empty then all explicitly allowed domains will be accessible. Example: \"*.github.com\" will block " +
                 "access to all subdomains of github.com.\n" +
                 "You can use domain names (\"pastebin.com\"), wilcards (\"*.pastebin.com\") or CIDR notation (\"127.0.0.0/8\")." );
 
@@ -220,7 +222,7 @@ public final class Config
 
             setOrder(
                 CATEGORY_HTTP,
-                httpEnable, httpWebsocketEnable, httpWhitelist, httpBlacklist,
+                httpEnable, httpWebsocketEnable, httpAllowedDomains, httpBlockedDomains,
                 httpTimeout, httpMaxRequests, httpMaxDownload, httpMaxUpload, httpMaxWebsockets, httpMaxWebsocketMessage
             );
         }
@@ -277,7 +279,7 @@ public final class Config
             renameProperty( CATEGORY_GENERAL, "turtlesCanPush", CATEGORY_TURTLE, "can_push" );
             renameProperty( CATEGORY_GENERAL, "turtle_disabled_actions", CATEGORY_TURTLE, "disabled_actions" );
 
-            config.getCategory( CATEGORY_HTTP )
+            config.getCategory( CATEGORY_TURTLE )
                 .setComment( "Various options relating to turtles." );
 
             turtlesNeedFuel = config.get( CATEGORY_TURTLE, "need_fuel", ComputerCraft.turtlesNeedFuel );
@@ -441,8 +443,8 @@ public final class Config
         // HTTP
         ComputerCraft.http_enable = httpEnable.getBoolean();
         ComputerCraft.http_websocket_enable = httpWebsocketEnable.getBoolean();
-        ComputerCraft.http_whitelist = new AddressPredicate( httpWhitelist.getStringList() );
-        ComputerCraft.http_blacklist = new AddressPredicate( httpBlacklist.getStringList() );
+        ComputerCraft.http_whitelist = new AddressPredicate( httpAllowedDomains.getStringList() );
+        ComputerCraft.http_blacklist = new AddressPredicate( httpBlockedDomains.getStringList() );
 
         ComputerCraft.httpTimeout = Math.max( 0, httpTimeout.getInt() );
         ComputerCraft.httpMaxRequests = Math.max( 1, httpMaxRequests.getInt() );

src/main/java/dan200/computercraft/shared/TurtleUpgrades.java

@@ -19,12 +19,35 @@ import net.minecraftforge.fml.common.ModContainer;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import java.util.*;
+import java.util.stream.Stream;
 
 public final class TurtleUpgrades
 {
+    public static class Wrapper
+    {
+        final ITurtleUpgrade upgrade;
+        final int legacyId;
+        final String id;
+        final String modId;
+        boolean enabled;
+
+        public Wrapper( ITurtleUpgrade upgrade )
+        {
+            ModContainer mc = Loader.instance().activeModContainer();
+
+            this.upgrade = upgrade;
+            this.legacyId = upgrade.getLegacyUpgradeID();
+            this.id = upgrade.getUpgradeID().toString();
+            this.modId = mc != null && mc.getModId() != null ? mc.getModId() : null;
+            this.enabled = true;
+        }
+    }
+
+    private static ITurtleUpgrade[] vanilla;
+
     private static final Map<String, ITurtleUpgrade> upgrades = new HashMap<>();
     private static final Int2ObjectMap<ITurtleUpgrade> legacyUpgrades = new Int2ObjectOpenHashMap<>();
-    private static final IdentityHashMap<ITurtleUpgrade, String> upgradeOwners = new IdentityHashMap<>();
+    private static final IdentityHashMap<ITurtleUpgrade, Wrapper> wrappers = new IdentityHashMap<>();
 
     private TurtleUpgrades() {}
 
@@ -35,9 +58,7 @@ public final class TurtleUpgrades
         int id = upgrade.getLegacyUpgradeID();
         if( id >= 0 && id < 64 )
         {
-            String message = getMessage( upgrade, "Legacy UpgradeID '" + id + "' is reserved by ComputerCraft" );
-            ComputerCraft.log.error( message );
-            throw new RuntimeException( message );
+            throw registrationError( upgrade, "Legacy Upgrade ID '" + id + "' is reserved by ComputerCraft" );
         }
 
         registerInternal( upgrade );
@@ -47,58 +68,63 @@ public final class TurtleUpgrades
     {
         Objects.requireNonNull( upgrade, "upgrade cannot be null" );
 
+        Wrapper wrapper = new Wrapper( upgrade );
+
         // Check conditions
-        int legacyId = upgrade.getLegacyUpgradeID();
+        int legacyId = wrapper.legacyId;
         if( legacyId >= 0 )
         {
             if( legacyId >= Short.MAX_VALUE )
             {
-                String message = getMessage( upgrade, "UpgradeID '" + legacyId + "' is out of range" );
-                ComputerCraft.log.error( message );
-                throw new RuntimeException( message );
+                throw registrationError( upgrade, "Upgrade ID '" + legacyId + "' is out of range" );
             }
 
             ITurtleUpgrade existing = legacyUpgrades.get( legacyId );
             if( existing != null )
             {
-                String message = getMessage( upgrade, "UpgradeID '" + legacyId + "' is already registered by '" + existing.getUnlocalisedAdjective() + " Turtle'" );
-                ComputerCraft.log.error( message );
-                throw new RuntimeException( message );
+                throw registrationError( upgrade, "Upgrade ID '" + legacyId + "' is already registered by '" + existing.getUnlocalisedAdjective() + " Turtle'" );
             }
         }
 
-        String id = upgrade.getUpgradeID().toString();
+        String id = wrapper.id;
         ITurtleUpgrade existing = upgrades.get( id );
         if( existing != null )
         {
-            String message = getMessage( upgrade, "UpgradeID '" + id + "' is already registered by '" + existing.getUnlocalisedAdjective() + " Turtle'" );
-            ComputerCraft.log.error( message );
-            throw new RuntimeException( message );
+            throw registrationError( upgrade, "Upgrade '" + id + "' is already registered by '" + existing.getUnlocalisedAdjective() + " Turtle'" );
         }
 
         // Register
         if( legacyId >= 0 ) legacyUpgrades.put( legacyId, upgrade );
         upgrades.put( id, upgrade );
-
-        ModContainer mc = Loader.instance().activeModContainer();
-        if( mc != null && mc.getModId() != null ) upgradeOwners.put( upgrade, mc.getModId() );
+        wrappers.put( upgrade, wrapper );
     }
 
-    private static String getMessage( ITurtleUpgrade upgrade, String rest )
+    private static RuntimeException registrationError( ITurtleUpgrade upgrade, String rest )
     {
-        return "Error registering '" + upgrade.getUnlocalisedAdjective() + " Turtle'. " + rest;
+        String message = "Error registering '" + upgrade.getUnlocalisedAdjective() + " Turtle'. " + rest;
+        ComputerCraft.log.error( message );
+        throw new IllegalArgumentException( message );
     }
 
+    @Nullable
     public static ITurtleUpgrade get( String id )
     {
         return upgrades.get( id );
     }
 
+    @Nullable
     public static ITurtleUpgrade get( int id )
     {
         return legacyUpgrades.get( id );
     }
 
+    @Nullable
+    public static String getOwner( @Nonnull ITurtleUpgrade upgrade )
+    {
+        Wrapper wrapper = wrappers.get( upgrade );
+        return wrapper != null ? wrapper.modId : null;
+    }
+
     public static ITurtleUpgrade get( @Nonnull ItemStack stack )
     {
         if( stack.isEmpty() ) return null;
@@ -115,25 +141,24 @@ public final class TurtleUpgrades
         return null;
     }
 
-    public static Iterable<ITurtleUpgrade> getVanillaUpgrades()
+    public static Stream<ITurtleUpgrade> getVanillaUpgrades()
     {
-        List<ITurtleUpgrade> vanilla = new ArrayList<>();
-        vanilla.add( ComputerCraft.TurtleUpgrades.diamondPickaxe );
-        vanilla.add( ComputerCraft.TurtleUpgrades.diamondAxe );
-        vanilla.add( ComputerCraft.TurtleUpgrades.diamondSword );
-        vanilla.add( ComputerCraft.TurtleUpgrades.diamondShovel );
-        vanilla.add( ComputerCraft.TurtleUpgrades.diamondHoe );
-        vanilla.add( ComputerCraft.TurtleUpgrades.craftingTable );
-        vanilla.add( ComputerCraft.TurtleUpgrades.wirelessModem );
-        vanilla.add( ComputerCraft.TurtleUpgrades.advancedModem );
-        vanilla.add( ComputerCraft.TurtleUpgrades.speaker );
-        return vanilla;
-    }
+        if( vanilla == null )
+        {
+            vanilla = new ITurtleUpgrade[] {
+                ComputerCraft.TurtleUpgrades.diamondPickaxe,
+                ComputerCraft.TurtleUpgrades.diamondAxe,
+                ComputerCraft.TurtleUpgrades.diamondSword,
+                ComputerCraft.TurtleUpgrades.diamondShovel,
+                ComputerCraft.TurtleUpgrades.diamondHoe,
+                ComputerCraft.TurtleUpgrades.craftingTable,
+                ComputerCraft.TurtleUpgrades.wirelessModem,
+                ComputerCraft.TurtleUpgrades.advancedModem,
+                ComputerCraft.TurtleUpgrades.speaker,
+            };
+        }
 
-    @Nullable
-    public static String getOwner( @Nonnull ITurtleUpgrade upgrade )
-    {
-        return upgradeOwners.get( upgrade );
+        return Arrays.stream( vanilla ).filter( x -> x != null && wrappers.get( x ).enabled );
     }
 
     public static Iterable<ITurtleUpgrade> getUpgrades()
@@ -145,4 +170,14 @@ public final class TurtleUpgrades
     {
         return true;
     }
+
+    public static void disable( ITurtleUpgrade upgrade )
+    {
+        Wrapper wrapper = wrappers.get( upgrade );
+        if( !wrapper.enabled ) return;
+
+        wrapper.enabled = false;
+        upgrades.remove( wrapper.id );
+        if( wrapper.legacyId >= 0 ) legacyUpgrades.remove( wrapper.legacyId );
+    }
 }

src/main/java/dan200/computercraft/shared/command/framework/CommandRoot.java

@@ -18,7 +18,7 @@ import java.util.List;
 import java.util.Map;
 
 /**
- * A command which delegates to a series of sub commands
+ * A command which delegates to a series of sub commands.
  */
 public class CommandRoot implements ISubCommand
 {

src/main/java/dan200/computercraft/shared/command/framework/ISubCommand.java

@@ -22,7 +22,7 @@ import java.util.List;
 public interface ISubCommand
 {
     /**
-     * Get the name of this command
+     * Get the name of this command.
      *
      * @return The name of this command
      * @see ICommand#getName()
@@ -40,7 +40,7 @@ public interface ISubCommand
     String getFullName();
 
     /**
-     * Get the usage of this command
+     * Get the usage of this command.
      *
      * @param context The context this command is executed in
      * @return The usage of this command
@@ -62,16 +62,17 @@ public interface ISubCommand
     boolean checkPermission( @Nonnull CommandContext context );
 
     /**
-     * Execute this command
+     * Execute this command.
      *
      * @param context   The current command context.
-     * @param arguments The arguments passed  @throws CommandException When an error occurs
+     * @param arguments The arguments passed
+     * @throws CommandException When an error occurs
      * @see ICommand#execute(MinecraftServer, ICommandSender, String[])
      */
     void execute( @Nonnull CommandContext context, @Nonnull List<String> arguments ) throws CommandException;
 
     /**
-     * Get a list of possible completions
+     * Get a list of possible completions.
      *
      * @param context   The current command context.
      * @param arguments The arguments passed. You should complete the last one.

src/main/java/dan200/computercraft/shared/command/text/ChatHelpers.java

@@ -15,7 +15,7 @@ import net.minecraft.util.text.event.ClickEvent;
 import net.minecraft.util.text.event.HoverEvent;
 
 /**
- * Various helpers for building chat messages
+ * Various helpers for building chat messages.
  */
 public final class ChatHelpers
 {

src/main/java/dan200/computercraft/shared/command/text/TableBuilder.java

@@ -107,7 +107,7 @@ public class TableBuilder
     }
 
     /**
-     * Trim this table to a given height
+     * Trim this table to a given height.
      *
      * @param height The desired height.
      */

src/main/java/dan200/computercraft/shared/command/text/TableFormatter.java

@@ -22,7 +22,7 @@ public interface TableFormatter
     ITextComponent HEADER = coloured( "=", TextFormatting.GRAY );
 
     /**
-     * Get additional padding for the component
+     * Get additional padding for the component.
      *
      * @param component The component to pad
      * @param width     The desired width for the component
@@ -32,7 +32,7 @@ public interface TableFormatter
     ITextComponent getPadding( ITextComponent component, int width );
 
     /**
-     * Get the minimum padding between each column
+     * Get the minimum padding between each column.
      *
      * @return The minimum padding.
      */

src/main/java/dan200/computercraft/shared/computer/apis/CommandAPI.java

@@ -30,8 +30,8 @@ import java.util.Collections;
 import java.util.HashMap;
 import java.util.Map;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.getInt;
-import static dan200.computercraft.core.apis.ArgumentHelper.getString;
+import static dan200.computercraft.api.lua.ArgumentHelper.getInt;
+import static dan200.computercraft.api.lua.ArgumentHelper.getString;
 
 public class CommandAPI implements ILuaAPI
 {
@@ -83,7 +83,7 @@ public class CommandAPI implements ILuaAPI
         {
             sender.clearOutput();
             int result = commandManager.executeCommand( sender, command );
-            return new Object[] { result > 0, sender.copyOutput() };
+            return new Object[] { result > 0, sender.copyOutput(), result };
         }
         catch( Throwable t )
         {
@@ -204,7 +204,7 @@ public class CommandAPI implements ILuaAPI
                     );
                     if( !world.isValid( min ) || !world.isValid( max ) )
                     {
-                        throw new LuaException( "Co-ordinates out or range" );
+                        throw new LuaException( "Co-ordinates out of range" );
                     }
                     if( (max.getX() - min.getX() + 1) * (max.getY() - min.getY() + 1) * (max.getZ() - min.getZ() + 1) > 4096 )
                     {
@@ -243,7 +243,7 @@ public class CommandAPI implements ILuaAPI
                     }
                     else
                     {
-                        throw new LuaException( "co-ordinates out or range" );
+                        throw new LuaException( "Co-ordinates out of range" );
                     }
                 } );
             }

src/main/java/dan200/computercraft/shared/computer/blocks/TileComputer.java

@@ -32,7 +32,7 @@ public class TileComputer extends TileComputerBase
         ServerComputer computer = new ServerComputer(
             getWorld(),
             id,
-            m_label,
+            label,
             instanceID,
             family,
             ComputerCraft.terminalWidth_computer,

src/main/java/dan200/computercraft/shared/computer/blocks/TileComputerBase.java

@@ -47,7 +47,7 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
 {
     private int m_instanceID = -1;
     private int m_computerID = -1;
-    protected String m_label = null;
+    protected String label = null;
     private boolean m_on = false;
     boolean m_startOn = false;
     private boolean m_fresh = false;
@@ -190,7 +190,7 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
 
                 m_fresh = false;
                 m_computerID = computer.getID();
-                m_label = computer.getLabel();
+                label = computer.getLabel();
                 m_on = computer.isOn();
 
                 if( computer.hasOutputChanged() ) updateOutput();
@@ -212,9 +212,9 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
         {
             nbt.setInteger( "computerID", m_computerID );
         }
-        if( m_label != null )
+        if( label != null )
         {
-            nbt.setString( "label", m_label );
+            nbt.setString( "label", label );
         }
         nbt.setBoolean( "on", m_on );
         return super.writeToNBT( nbt );
@@ -248,7 +248,7 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
         m_computerID = id;
 
         // Load label
-        m_label = nbt.hasKey( "label" ) ? nbt.getString( "label" ) : null;
+        label = nbt.hasKey( "label" ) ? nbt.getString( "label" ) : null;
 
         // Load power state
         m_startOn = nbt.getBoolean( "on" );
@@ -280,7 +280,7 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
     }
 
     /**
-     * Gets the redstone input for an adjacent block
+     * Gets the redstone input for an adjacent block.
      *
      * @param world The world we exist in
      * @param pos   The position of the neighbour
@@ -361,7 +361,7 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
     @Override
     public final String getLabel()
     {
-        return m_label;
+        return label;
     }
 
     @Override
@@ -378,9 +378,9 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
     @Override
     public final void setLabel( String label )
     {
-        if( getWorld().isRemote || Objects.equals( m_label, label ) ) return;
+        if( getWorld().isRemote || Objects.equals( this.label, label ) ) return;
 
-        m_label = label;
+        this.label = label;
         ServerComputer computer = getServerComputer();
         if( computer != null ) computer.setLabel( label );
         markDirty();
@@ -453,8 +453,8 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
     protected void writeDescription( @Nonnull NBTTagCompound nbt )
     {
         super.writeDescription( nbt );
-        nbt.setInteger( "instanceID", createServerComputer().getInstanceID() );
-        if( m_label != null ) nbt.setString( "label", m_label );
+        if( m_instanceID >= 0 ) nbt.setInteger( "instanceID", m_instanceID );
+        if( label != null ) nbt.setString( "label", label );
         if( m_computerID >= 0 ) nbt.setInteger( "computerID", m_computerID );
     }
 
@@ -463,7 +463,7 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
     {
         super.readDescription( nbt );
         m_instanceID = nbt.getInteger( "instanceID" );
-        m_label = nbt.hasKey( "label" ) ? nbt.getString( "label" ) : null;
+        label = nbt.hasKey( "label" ) ? nbt.getString( "label" ) : null;
         m_computerID = nbt.hasKey( "computerID" ) ? nbt.getInteger( "computerID" ) : -1;
     }
 
@@ -474,7 +474,7 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
             unload();
             m_instanceID = copy.m_instanceID;
             m_computerID = copy.m_computerID;
-            m_label = copy.m_label;
+            label = copy.label;
             m_on = copy.m_on;
             m_startOn = copy.m_startOn;
             updateBlock();
@@ -493,13 +493,13 @@ public abstract class TileComputerBase extends TileGeneric implements IComputerT
     @Override
     public String getName()
     {
-        return hasCustomName() ? m_label : getBlockType().getTranslationKey();
+        return hasCustomName() ? label : getBlockType().getTranslationKey();
     }
 
     @Override
     public boolean hasCustomName()
     {
-        return !Strings.isNullOrEmpty( m_label );
+        return !Strings.isNullOrEmpty( label );
     }
 
     @Nonnull

src/main/java/dan200/computercraft/shared/computer/core/InputHandler.java

@@ -7,7 +7,7 @@
 package dan200.computercraft.shared.computer.core;
 
 /**
- * Receives some input and forwards it to a computer
+ * Receives some input and forwards it to a computer.
  *
  * @see InputState
  * @see IComputer

src/main/java/dan200/computercraft/shared/integration/crafttweaker/TurtleTweaker.java

@@ -0,0 +1,70 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.shared.integration.crafttweaker;
+
+import crafttweaker.CraftTweakerAPI;
+import crafttweaker.annotations.ModOnly;
+import crafttweaker.annotations.ZenDoc;
+import crafttweaker.annotations.ZenRegister;
+import crafttweaker.api.item.IItemStack;
+import crafttweaker.api.minecraft.CraftTweakerMC;
+import dan200.computercraft.ComputerCraft;
+import dan200.computercraft.shared.integration.crafttweaker.actions.AddTurtleTool;
+import dan200.computercraft.shared.integration.crafttweaker.actions.RemoveTurtleUpgradeByItem;
+import dan200.computercraft.shared.integration.crafttweaker.actions.RemoveTurtleUpgradeByName;
+import stanhebben.zenscript.annotations.ZenClass;
+import stanhebben.zenscript.annotations.ZenMethod;
+
+@ZenRegister
+@ZenClass( "dan200.computercraft.turtle" )
+@ModOnly( ComputerCraft.MOD_ID )
+public class TurtleTweaker
+{
+    @ZenMethod
+    @ZenDoc( "Remove a turtle upgrade with the given id" )
+    public static void removeUpgrade( String upgrade )
+    {
+        CraftTweakerAPI.apply( new RemoveTurtleUpgradeByName( upgrade ) );
+    }
+
+    @ZenMethod
+    @ZenDoc( "Remove a turtle upgrade crafted with the given item stack" )
+    public static void removeUpgrade( IItemStack stack )
+    {
+        CraftTweakerAPI.apply( new RemoveTurtleUpgradeByItem( CraftTweakerMC.getItemStack( stack ) ) );
+    }
+
+    @ZenMethod
+    @ZenDoc( "Add a new turtle tool with the given id, which crafts and acts using the given stack." )
+    public static void addTool( String id, IItemStack stack )
+    {
+        addTool( id, stack, stack, "tool" );
+    }
+
+    @ZenMethod
+    @ZenDoc( "Add a new turtle tool with the given id, which is crafted with one item, and uses another." )
+    public static void addTool( String id, IItemStack craftingStack, IItemStack toolStack )
+    {
+        addTool( id, craftingStack, toolStack, "tool" );
+    }
+
+    @ZenMethod
+    @ZenDoc( "Add a new turtle tool with the given id, which crafts and acts using the given stack. You may also" +
+        "specify a 'kind' of tool, which limits what blocks the turtle can break (for instance, an 'axe' may only break wood)." )
+    public static void addTool( String id, IItemStack stack, String kind )
+    {
+        addTool( id, stack, stack, kind );
+    }
+
+    @ZenMethod
+    @ZenDoc( "Add a new turtle tool with the given id, which is crafted with one item, and uses another. You may also" +
+        "specify a 'kind' of tool, which limits what blocks the turtle can break (for instance, an 'axe' may only break wood)." )
+    public static void addTool( String id, IItemStack craftingStack, IItemStack toolStack, String kind )
+    {
+        CraftTweakerAPI.apply( new AddTurtleTool( id, CraftTweakerMC.getItemStack( craftingStack ), CraftTweakerMC.getItemStack( toolStack ), kind ) );
+    }
+}

src/main/java/dan200/computercraft/shared/integration/crafttweaker/actions/AddTurtleTool.java

@@ -0,0 +1,96 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.shared.integration.crafttweaker.actions;
+
+import dan200.computercraft.ComputerCraft;
+import dan200.computercraft.shared.TurtleUpgrades;
+import dan200.computercraft.shared.turtle.upgrades.*;
+import net.minecraft.item.ItemStack;
+import net.minecraft.util.ResourceLocation;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Optional;
+
+/**
+ * Register a new turtle tool.
+ */
+public class AddTurtleTool implements IAction
+{
+    private interface Factory
+    {
+        TurtleTool create( ResourceLocation location, ItemStack craftItem, ItemStack toolItem );
+    }
+
+    private static final Map<String, Factory> kinds = new HashMap<>();
+
+    static
+    {
+        kinds.put( "tool", TurtleTool::new );
+        kinds.put( "axe", TurtleAxe::new );
+        kinds.put( "hoe", TurtleHoe::new );
+        kinds.put( "shovel", TurtleShovel::new );
+        kinds.put( "sword", TurtleSword::new );
+    }
+
+    private final String id;
+    private final ItemStack craftItem;
+    private final ItemStack toolItem;
+    private final String kind;
+
+    public AddTurtleTool( String id, ItemStack craftItem, ItemStack toolItem, String kind )
+    {
+        this.id = id;
+        this.craftItem = craftItem;
+        this.toolItem = toolItem;
+        this.kind = kind;
+    }
+
+    @Override
+    public void apply()
+    {
+        Factory factory = kinds.get( kind );
+        if( factory == null )
+        {
+            ComputerCraft.log.error( "Unknown turtle upgrade kind '{}' (this should have been rejected by verify!)", kind );
+            return;
+        }
+
+        try
+        {
+            TurtleUpgrades.register( factory.create( new ResourceLocation( id ), craftItem, toolItem ) );
+        }
+        catch( RuntimeException e )
+        {
+            ComputerCraft.log.error( "Registration of turtle tool failed", e );
+        }
+    }
+
+    @Override
+    public String describe()
+    {
+        return String.format( "Add new turtle %s '%s' (crafted with '%s', uses a '%s')", kind, id, craftItem, toolItem );
+    }
+
+    public Optional<String> getValidationProblem()
+    {
+        if( craftItem.isEmpty() ) return Optional.of( "Crafting item stack is empty." );
+        if( craftItem.hasTagCompound() && !craftItem.getTagCompound().isEmpty() )
+        {
+            return Optional.of( "Crafting item has NBT." );
+        }
+        if( toolItem.isEmpty() ) return Optional.of( "Tool item stack is empty." );
+        if( !kinds.containsKey( kind ) ) return Optional.of( String.format( "Unknown kind '%s'.", kind ) );
+
+        if( TurtleUpgrades.get( id ) != null )
+        {
+            return Optional.of( String.format( "An upgrade with the same name ('%s') has already been registered.", id ) );
+        }
+
+        return Optional.empty();
+    }
+}

src/main/java/dan200/computercraft/shared/integration/crafttweaker/actions/IAction.java

@@ -0,0 +1,32 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.shared.integration.crafttweaker.actions;
+
+import java.util.Optional;
+
+/**
+ * An extension of {@link IAction} with a single validation function, rather than two.
+ */
+public interface IAction extends crafttweaker.IAction
+{
+    default Optional<String> getValidationProblem()
+    {
+        return Optional.empty();
+    }
+
+    @Override
+    default boolean validate()
+    {
+        return !getValidationProblem().isPresent();
+    }
+
+    @Override
+    default String describeInvalid()
+    {
+        return getValidationProblem().orElse( "No problems found." );
+    }
+}

src/main/java/dan200/computercraft/shared/integration/crafttweaker/actions/RemoveTurtleUpgradeByItem.java

@@ -0,0 +1,50 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.shared.integration.crafttweaker.actions;
+
+import dan200.computercraft.api.turtle.ITurtleUpgrade;
+import dan200.computercraft.shared.TurtleUpgrades;
+import net.minecraft.item.ItemStack;
+
+import java.util.Optional;
+
+/**
+ * Removes a turtle upgrade crafted with the given stack.
+ */
+public class RemoveTurtleUpgradeByItem implements IAction
+{
+    private final ItemStack stack;
+
+    public RemoveTurtleUpgradeByItem( ItemStack stack )
+    {
+        this.stack = stack;
+    }
+
+    @Override
+    public void apply()
+    {
+        ITurtleUpgrade upgrade = TurtleUpgrades.get( stack );
+        if( upgrade != null ) TurtleUpgrades.disable( upgrade );
+    }
+
+    @Override
+    public String describe()
+    {
+        return String.format( "Remove turtle upgrades crafted with '%s'", stack );
+    }
+
+    @Override
+    public Optional<String> getValidationProblem()
+    {
+        if( TurtleUpgrades.get( stack ) == null )
+        {
+            return Optional.of( String.format( "Unknown turtle upgrade crafted with '%s'.", stack ) );
+        }
+
+        return Optional.empty();
+    }
+}

src/main/java/dan200/computercraft/shared/integration/crafttweaker/actions/RemoveTurtleUpgradeByName.java

@@ -0,0 +1,49 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.shared.integration.crafttweaker.actions;
+
+import dan200.computercraft.api.turtle.ITurtleUpgrade;
+import dan200.computercraft.shared.TurtleUpgrades;
+
+import java.util.Optional;
+
+/**
+ * Removes a turtle upgrade with the given id.
+ */
+public class RemoveTurtleUpgradeByName implements IAction
+{
+    private final String id;
+
+    public RemoveTurtleUpgradeByName( String id )
+    {
+        this.id = id;
+    }
+
+    @Override
+    public void apply()
+    {
+        ITurtleUpgrade upgrade = TurtleUpgrades.get( id );
+        if( upgrade != null ) TurtleUpgrades.disable( upgrade );
+    }
+
+    @Override
+    public String describe()
+    {
+        return String.format( "Remove turtle upgrade '%s'", id );
+    }
+
+    @Override
+    public Optional<String> getValidationProblem()
+    {
+        if( TurtleUpgrades.get( id ) == null )
+        {
+            return Optional.of( String.format( "Unknown turtle upgrade '%s'.", id ) );
+        }
+
+        return Optional.empty();
+    }
+}

src/main/java/dan200/computercraft/shared/integration/jei/JEIComputerCraft.java

@@ -108,7 +108,7 @@ public class JEIComputerCraft implements IModPlugin
     }
 
     /**
-     * Distinguishes turtles by upgrades and family
+     * Distinguishes turtles by upgrades and family.
      */
     private static final ISubtypeInterpreter turtleSubtype = stack -> {
         Item item = stack.getItem();
@@ -132,7 +132,7 @@ public class JEIComputerCraft implements IModPlugin
     };
 
     /**
-     * Distinguishes pocket computers by upgrade and family
+     * Distinguishes pocket computers by upgrade and family.
      */
     private static final ISubtypeInterpreter pocketSubtype = stack -> {
         Item item = stack.getItem();
@@ -152,7 +152,7 @@ public class JEIComputerCraft implements IModPlugin
     };
 
     /**
-     * Distinguishes disks by colour
+     * Distinguishes disks by colour.
      */
     private static final ISubtypeInterpreter diskSubtype = stack -> {
         Item item = stack.getItem();

src/main/java/dan200/computercraft/shared/media/inventory/ContainerHeldItem.java

@@ -6,7 +6,6 @@
 
 package dan200.computercraft.shared.media.inventory;
 
-import dan200.computercraft.shared.util.InventoryUtil;
 import net.minecraft.entity.player.EntityPlayer;
 import net.minecraft.inventory.Container;
 import net.minecraft.item.ItemStack;
@@ -22,7 +21,7 @@ public class ContainerHeldItem extends Container
     public ContainerHeldItem( EntityPlayer player, EnumHand hand )
     {
         m_hand = hand;
-        m_stack = InventoryUtil.copyItem( player.getHeldItem( hand ) );
+        m_stack = player.getHeldItem( hand ).copy();
     }
 
     @Nonnull

src/main/java/dan200/computercraft/shared/media/items/RecordMedia.java

@@ -15,7 +15,7 @@ import net.minecraft.util.SoundEvent;
 import javax.annotation.Nonnull;
 
 /**
- * An implementation of IMedia for ItemRecord's
+ * An implementation of IMedia for ItemRecords.
  */
 public final class RecordMedia implements IMedia
 {

src/main/java/dan200/computercraft/shared/network/NetworkHandler.java

@@ -72,6 +72,7 @@ public final class NetworkHandler
      * /**
      * Register packet, and a thread-unsafe handler for it.
      *
+     * @param <T>     The type of the packet to send.
      * @param id      The identifier for this packet type
      * @param side    The side to register this packet handler under
      * @param factory The factory for this type of packet.

src/main/java/dan200/computercraft/shared/peripheral/commandblock/CommandBlockPeripheral.java

@@ -14,7 +14,7 @@ import net.minecraft.tileentity.TileEntityCommandBlock;
 
 import javax.annotation.Nonnull;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.getString;
+import static dan200.computercraft.api.lua.ArgumentHelper.getString;
 
 public class CommandBlockPeripheral implements IPeripheral
 {

src/main/java/dan200/computercraft/shared/peripheral/diskdrive/DiskDrivePeripheral.java

@@ -11,6 +11,7 @@ import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.api.media.IMedia;
 import dan200.computercraft.api.peripheral.IComputerAccess;
 import dan200.computercraft.api.peripheral.IPeripheral;
+import dan200.computercraft.shared.MediaProviders;
 import dan200.computercraft.shared.media.items.ItemDiskLegacy;
 import dan200.computercraft.shared.util.StringUtil;
 import net.minecraft.item.Item;
@@ -18,13 +19,13 @@ import net.minecraft.item.ItemStack;
 
 import javax.annotation.Nonnull;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.optString;
+import static dan200.computercraft.api.lua.ArgumentHelper.optString;
 
-public class DiskDrivePeripheral implements IPeripheral
+class DiskDrivePeripheral implements IPeripheral
 {
     private final TileDiskDrive m_diskDrive;
 
-    public DiskDrivePeripheral( TileDiskDrive diskDrive )
+    DiskDrivePeripheral( TileDiskDrive diskDrive )
     {
         m_diskDrive = diskDrive;
     }
@@ -56,7 +57,7 @@ public class DiskDrivePeripheral implements IPeripheral
     }
 
     @Override
-    public Object[] callMethod( @Nonnull IComputerAccess computer, @Nonnull ILuaContext context, int method, @Nonnull Object[] arguments ) throws LuaException
+    public Object[] callMethod( @Nonnull IComputerAccess computer, @Nonnull ILuaContext context, int method, @Nonnull Object[] arguments ) throws LuaException, InterruptedException
     {
         switch( method )
         {
@@ -64,21 +65,26 @@ public class DiskDrivePeripheral implements IPeripheral
                 return new Object[] { !m_diskDrive.getDiskStack().isEmpty() };
             case 1: // getDiskLabel
             {
-                IMedia media = m_diskDrive.getDiskMedia();
-                return media == null ? null : new Object[] { media.getLabel( m_diskDrive.getDiskStack() ) };
+                ItemStack stack = m_diskDrive.getDiskStack();
+                IMedia media = MediaProviders.get( stack );
+                return media == null ? null : new Object[] { media.getLabel( stack ) };
             }
             case 2: // setDiskLabel
             {
                 String label = optString( arguments, 0, null );
 
-                IMedia media = m_diskDrive.getDiskMedia();
-                if( media == null ) return null;
+                return context.executeMainThreadTask( () -> {
+                    ItemStack stack = m_diskDrive.getDiskStack();
+                    IMedia media = MediaProviders.get( stack );
+                    if( media == null ) return null;
 
-                ItemStack disk = m_diskDrive.getDiskStack();
-                label = StringUtil.normaliseLabel( label );
-                if( !media.setLabel( disk, label ) ) throw new LuaException( "Disk label cannot be changed" );
-                m_diskDrive.setDiskStack( disk );
-                return null;
+                    if( !media.setLabel( stack, StringUtil.normaliseLabel( label ) ) )
+                    {
+                        throw new LuaException( "Disk label cannot be changed" );
+                    }
+                    m_diskDrive.setDiskStack( stack );
+                    return null;
+                } );
             }
             case 3: // hasData
                 return new Object[] { m_diskDrive.getDiskMountPath( computer ) != null };
@@ -87,14 +93,16 @@ public class DiskDrivePeripheral implements IPeripheral
             case 5:
             {
                 // hasAudio
-                IMedia media = m_diskDrive.getDiskMedia();
-                return new Object[] { media != null && media.getAudio( m_diskDrive.getDiskStack() ) != null };
+                ItemStack stack = m_diskDrive.getDiskStack();
+                IMedia media = MediaProviders.get( stack );
+                return new Object[] { media != null && media.getAudio( stack ) != null };
             }
             case 6:
             {
                 // getAudioTitle
-                IMedia media = m_diskDrive.getDiskMedia();
-                return new Object[] { media != null ? media.getAudioTitle( m_diskDrive.getDiskStack() ) : false };
+                ItemStack stack = m_diskDrive.getDiskStack();
+                IMedia media = MediaProviders.get( stack );
+                return new Object[] { media != null ? media.getAudioTitle( stack ) : false };
             }
             case 7: // playAudio
                 m_diskDrive.playDiskAudio();
@@ -131,8 +139,7 @@ public class DiskDrivePeripheral implements IPeripheral
     @Override
     public boolean equals( IPeripheral other )
     {
-        if( this == other ) return true;
-        return other instanceof DiskDrivePeripheral && ((DiskDrivePeripheral) other).m_diskDrive == m_diskDrive;
+        return this == other || other instanceof DiskDrivePeripheral && ((DiskDrivePeripheral) other).m_diskDrive == m_diskDrive;
     }
 
     @Nonnull

src/main/java/dan200/computercraft/shared/peripheral/diskdrive/TileDiskDrive.java

@@ -318,35 +318,31 @@ public class TileDiskDrive extends TilePeripheralBase implements DefaultInventor
     }
 
     @Nonnull
-    public ItemStack getDiskStack()
+    ItemStack getDiskStack()
     {
         return getStackInSlot( 0 );
     }
 
-    public void setDiskStack( @Nonnull ItemStack stack )
+    void setDiskStack( @Nonnull ItemStack stack )
     {
         setInventorySlotContents( 0, stack );
     }
 
-    public IMedia getDiskMedia()
+    private IMedia getDiskMedia()
     {
         return MediaProviders.get( getDiskStack() );
     }
 
-    public String getDiskMountPath( IComputerAccess computer )
+    String getDiskMountPath( IComputerAccess computer )
     {
         synchronized( this )
         {
-            if( m_computers.containsKey( computer ) )
-            {
-                MountInfo info = m_computers.get( computer );
-                return info.mountPath;
-            }
+            MountInfo info = m_computers.get( computer );
+            return info != null ? info.mountPath : null;
         }
-        return null;
     }
 
-    public void mount( IComputerAccess computer )
+    void mount( IComputerAccess computer )
     {
         synchronized( this )
         {
@@ -355,7 +351,7 @@ public class TileDiskDrive extends TilePeripheralBase implements DefaultInventor
         }
     }
 
-    public void unmount( IComputerAccess computer )
+    void unmount( IComputerAccess computer )
     {
         synchronized( this )
         {
@@ -364,7 +360,7 @@ public class TileDiskDrive extends TilePeripheralBase implements DefaultInventor
         }
     }
 
-    public void playDiskAudio()
+    void playDiskAudio()
     {
         synchronized( this )
         {
@@ -377,7 +373,7 @@ public class TileDiskDrive extends TilePeripheralBase implements DefaultInventor
         }
     }
 
-    public void stopDiskAudio()
+    void stopDiskAudio()
     {
         synchronized( this )
         {
@@ -386,7 +382,7 @@ public class TileDiskDrive extends TilePeripheralBase implements DefaultInventor
         }
     }
 
-    public void ejectDisk()
+    void ejectDisk()
     {
         synchronized( this )
         {

src/main/java/dan200/computercraft/shared/peripheral/modem/ModemPeripheral.java

@@ -21,7 +21,7 @@ import javax.annotation.Nonnull;
 import java.util.HashSet;
 import java.util.Set;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.getInt;
+import static dan200.computercraft.api.lua.ArgumentHelper.getInt;
 
 public abstract class ModemPeripheral implements IPeripheral, IPacketSender, IPacketReceiver
 {

src/main/java/dan200/computercraft/shared/peripheral/modem/WirelessModemPeripheral.java

@@ -7,8 +7,11 @@
 package dan200.computercraft.shared.peripheral.modem;
 
 /**
- * This only exists for backwards compatibility
+ * This only exists for backwards compatibility.
+ *
+ * @deprecated Use {@link dan200.computercraft.shared.peripheral.modem.wireless.WirelessModemPeripheral} instead.
  */
+@Deprecated
 public abstract class WirelessModemPeripheral extends dan200.computercraft.shared.peripheral.modem.wireless.WirelessModemPeripheral
 {
     @Deprecated

src/main/java/dan200/computercraft/shared/peripheral/modem/wired/WiredModemLocalPeripheral.java

@@ -23,7 +23,7 @@ import java.util.Collections;
 import java.util.Map;
 
 /**
- * Represents a local peripheral exposed on the wired network
+ * Represents a local peripheral exposed on the wired network.
  *
  * This is responsible for getting the peripheral in world, tracking id and type and determining whether
  * it has changed.
@@ -39,7 +39,7 @@ public final class WiredModemLocalPeripheral
     private IPeripheral peripheral;
 
     /**
-     * Attach a new peripheral from the world
+     * Attach a new peripheral from the world.
      *
      * @param world     The world to search in
      * @param origin    The position to search from
@@ -76,7 +76,7 @@ public final class WiredModemLocalPeripheral
     }
 
     /**
-     * Detach the current peripheral
+     * Detach the current peripheral.
      *
      * @return Whether the peripheral changed
      */

src/main/java/dan200/computercraft/shared/peripheral/modem/wired/WiredModemPeripheral.java

@@ -28,7 +28,7 @@ import java.util.Map;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ConcurrentMap;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.getString;
+import static dan200.computercraft.api.lua.ArgumentHelper.getString;
 
 public abstract class WiredModemPeripheral extends ModemPeripheral implements IWiredSender
 {

src/main/java/dan200/computercraft/shared/peripheral/monitor/MonitorPeripheral.java

@@ -17,7 +17,7 @@ import org.apache.commons.lang3.ArrayUtils;
 
 import javax.annotation.Nonnull;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.*;
+import static dan200.computercraft.api.lua.ArgumentHelper.*;
 
 public class MonitorPeripheral implements IPeripheral
 {
@@ -123,7 +123,7 @@ public class MonitorPeripheral implements IPeripheral
             case 8:
             {
                 // setTextScale
-                int scale = (int) (getReal( args, 0 ) * 2.0);
+                int scale = (int) (getFiniteDouble( args, 0 ) * 2.0);
                 if( scale < 1 || scale > 10 )
                 {
                     throw new LuaException( "Expected number in range 0.5-5" );
@@ -184,9 +184,9 @@ public class MonitorPeripheral implements IPeripheral
                 }
                 else
                 {
-                    double r = getReal( args, 1 );
-                    double g = getReal( args, 2 );
-                    double b = getReal( args, 3 );
+                    double r = getFiniteDouble( args, 1 );
+                    double g = getFiniteDouble( args, 2 );
+                    double b = getFiniteDouble( args, 3 );
                     TermAPI.setColour( terminal, colour, r, g, b );
                 }
                 return null;

src/main/java/dan200/computercraft/shared/peripheral/printer/PrinterPeripheral.java

@@ -11,11 +11,12 @@ import dan200.computercraft.api.lua.LuaException;
 import dan200.computercraft.api.peripheral.IComputerAccess;
 import dan200.computercraft.api.peripheral.IPeripheral;
 import dan200.computercraft.core.terminal.Terminal;
+import dan200.computercraft.shared.util.StringUtil;
 
 import javax.annotation.Nonnull;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.getInt;
-import static dan200.computercraft.core.apis.ArgumentHelper.optString;
+import static dan200.computercraft.api.lua.ArgumentHelper.getInt;
+import static dan200.computercraft.api.lua.ArgumentHelper.optString;
 
 public class PrinterPeripheral implements IPeripheral
 {
@@ -51,8 +52,13 @@ public class PrinterPeripheral implements IPeripheral
     }
 
     @Override
-    public Object[] callMethod( @Nonnull IComputerAccess computer, @Nonnull ILuaContext context, int method, @Nonnull Object[] args ) throws LuaException
+    public Object[] callMethod( @Nonnull IComputerAccess computer, @Nonnull ILuaContext context, int method, @Nonnull Object[] args ) throws LuaException, InterruptedException
     {
+        // FIXME: There's a theoretical race condition here between getCurrentPage and then using the page. Ideally
+        //  we'd lock on the page, consume it, and unlock.
+
+        // FIXME: None of our page modification functions actually mark the tile as dirty, so the page may not be
+        //  persisted correctly.
         switch( method )
         {
             case 0: // write
@@ -89,10 +95,13 @@ public class PrinterPeripheral implements IPeripheral
                 return new Object[] { width, height };
             }
             case 4: // newPage
-                return new Object[] { m_printer.startNewPage() };
+                return context.executeMainThreadTask( () -> new Object[] { m_printer.startNewPage() } );
             case 5: // endPage
                 getCurrentPage();
-                return new Object[] { m_printer.endCurrentPage() };
+                return context.executeMainThreadTask( () -> {
+                    getCurrentPage();
+                    return new Object[] { m_printer.endCurrentPage() };
+                } );
             case 6: // getInkLevel
                 return new Object[] { m_printer.getInkLevel() };
             case 7:
@@ -100,7 +109,7 @@ public class PrinterPeripheral implements IPeripheral
                 // setPageTitle
                 String title = optString( args, 0, "" );
                 getCurrentPage();
-                m_printer.setPageTitle( title );
+                m_printer.setPageTitle( StringUtil.normaliseLabel( title ) );
                 return null;
             }
             case 8: // getPaperLevel
@@ -123,13 +132,11 @@ public class PrinterPeripheral implements IPeripheral
         return m_printer;
     }
 
+    @Nonnull
     private Terminal getCurrentPage() throws LuaException
     {
         Terminal currentPage = m_printer.getCurrentPage();
-        if( currentPage == null )
-        {
-            throw new LuaException( "Page not started" );
-        }
+        if( currentPage == null ) throw new LuaException( "Page not started" );
         return currentPage;
     }
 }

src/main/java/dan200/computercraft/shared/peripheral/printer/TilePrinter.java

@@ -45,9 +45,9 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
 {
     // Statics
 
-    private static final int[] bottomSlots = new int[] { 7, 8, 9, 10, 11, 12 };
-    private static final int[] topSlots = new int[] { 1, 2, 3, 4, 5, 6 };
-    private static final int[] sideSlots = new int[] { 0 };
+    private static final int[] BOTTOM_SLOTS = new int[] { 7, 8, 9, 10, 11, 12 };
+    private static final int[] TOP_SLOTS = new int[] { 1, 2, 3, 4, 5, 6 };
+    private static final int[] SIDE_SLOTS = new int[] { 0 };
 
     // Members
 
@@ -88,18 +88,12 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         }
 
         // Read inventory
-        synchronized( m_inventory )
+        NBTTagList itemList = nbt.getTagList( "Items", Constants.NBT.TAG_COMPOUND );
+        for( int i = 0; i < itemList.tagCount(); i++ )
         {
-            NBTTagList nbttaglist = nbt.getTagList( "Items", Constants.NBT.TAG_COMPOUND );
-            for( int i = 0; i < nbttaglist.tagCount(); i++ )
-            {
-                NBTTagCompound itemTag = nbttaglist.getCompoundTagAt( i );
-                int j = itemTag.getByte( "Slot" ) & 0xff;
-                if( j < m_inventory.size() )
-                {
-                    m_inventory.set( j, new ItemStack( itemTag ) );
-                }
-            }
+            NBTTagCompound itemTag = itemList.getCompoundTagAt( i );
+            int slot = itemTag.getByte( "Slot" ) & 0xff;
+            if( slot < m_inventory.size() ) m_inventory.set( slot, new ItemStack( itemTag ) );
         }
     }
 
@@ -116,21 +110,18 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         }
 
         // Write inventory
-        synchronized( m_inventory )
+        NBTTagList itemList = new NBTTagList();
+        for( int i = 0; i < m_inventory.size(); i++ )
         {
-            NBTTagList nbttaglist = new NBTTagList();
-            for( int i = 0; i < m_inventory.size(); i++ )
-            {
-                if( !m_inventory.get( i ).isEmpty() )
-                {
-                    NBTTagCompound tag = new NBTTagCompound();
-                    tag.setByte( "Slot", (byte) i );
-                    m_inventory.get( i ).writeToNBT( tag );
-                    nbttaglist.appendTag( tag );
-                }
-            }
-            nbt.setTag( "Items", nbttaglist );
+            ItemStack stack = m_inventory.get( i );
+            if( stack.isEmpty() ) continue;
+
+            NBTTagCompound tag = new NBTTagCompound();
+            tag.setByte( "Slot", (byte) i );
+            stack.writeToNBT( tag );
+            itemList.appendTag( tag );
         }
+        nbt.setTag( "Items", itemList );
 
         return super.writeToNBT( nbt );
     }
@@ -148,7 +139,7 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         return super.shouldRefresh( world, pos, oldState, newState ) || BlockPeripheral.getPeripheralType( newState ) != PeripheralType.Printer;
     }
 
-    public boolean isPrinting()
+    boolean isPrinting()
     {
         return m_printing;
     }
@@ -173,73 +164,59 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
 
     @Nonnull
     @Override
-    public ItemStack getStackInSlot( int i )
+    public ItemStack getStackInSlot( int slot )
     {
-        return m_inventory.get( i );
+        return m_inventory.get( slot );
     }
 
     @Nonnull
     @Override
-    public ItemStack removeStackFromSlot( int i )
+    public ItemStack removeStackFromSlot( int slot )
     {
-        synchronized( m_inventory )
-        {
-            ItemStack result = m_inventory.get( i );
-            m_inventory.set( i, ItemStack.EMPTY );
-            markDirty();
-            updateAnim();
-            return result;
-        }
+        ItemStack result = m_inventory.get( slot );
+        m_inventory.set( slot, ItemStack.EMPTY );
+        markDirty();
+        updateAnim();
+        return result;
     }
 
     @Nonnull
     @Override
-    public ItemStack decrStackSize( int i, int j )
+    public ItemStack decrStackSize( int slot, int count )
     {
-        synchronized( m_inventory )
+        ItemStack stack = m_inventory.get( slot );
+        if( stack.isEmpty() ) return ItemStack.EMPTY;
+
+        if( stack.getCount() <= count )
         {
-            if( m_inventory.get( i ).isEmpty() ) return ItemStack.EMPTY;
-
-            if( m_inventory.get( i ).getCount() <= j )
-            {
-                ItemStack itemstack = m_inventory.get( i );
-                m_inventory.set( i, ItemStack.EMPTY );
-                markDirty();
-                updateAnim();
-                return itemstack;
-            }
-
-            ItemStack part = m_inventory.get( i ).splitStack( j );
-            if( m_inventory.get( i ).isEmpty() )
-            {
-                m_inventory.set( i, ItemStack.EMPTY );
-                updateAnim();
-            }
-            markDirty();
-            return part;
+            setInventorySlotContents( slot, ItemStack.EMPTY );
+            return stack;
         }
+
+        ItemStack part = stack.splitStack( count );
+        if( m_inventory.get( slot ).isEmpty() )
+        {
+            m_inventory.set( slot, ItemStack.EMPTY );
+            updateAnim();
+        }
+        markDirty();
+        return part;
     }
 
     @Override
-    public void setInventorySlotContents( int i, @Nonnull ItemStack stack )
+    public void setInventorySlotContents( int slot, @Nonnull ItemStack stack )
     {
-        synchronized( m_inventory )
-        {
-            m_inventory.set( i, stack );
-            markDirty();
-            updateAnim();
-        }
+        m_inventory.set( slot, stack );
+        markDirty();
+        updateAnim();
     }
 
     @Override
     public void clear()
     {
-        synchronized( m_inventory )
-        {
-            for( int i = 0; i < m_inventory.size(); i++ ) m_inventory.set( i, ItemStack.EMPTY );
-            markDirty();
-            updateAnim();
-        }
+        for( int i = 0; i < m_inventory.size(); i++ ) m_inventory.set( i, ItemStack.EMPTY );
+        markDirty();
+        updateAnim();
     }
 
     @Override
@@ -249,7 +226,7 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         {
             return isInk( stack );
         }
-        else if( slot >= topSlots[0] && slot <= topSlots[topSlots.length - 1] )
+        else if( slot >= TOP_SLOTS[0] && slot <= TOP_SLOTS[TOP_SLOTS.length - 1] )
         {
             return isPaper( stack );
         }
@@ -295,11 +272,11 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         switch( side )
         {
             case DOWN: // Bottom (Out tray)
-                return bottomSlots;
+                return BOTTOM_SLOTS;
             case UP: // Top (In tray)
-                return topSlots;
+                return TOP_SLOTS;
             default: // Sides (Ink)
-                return sideSlots;
+                return SIDE_SLOTS;
         }
     }
 
@@ -311,14 +288,18 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         return new PrinterPeripheral( this );
     }
 
-    public Terminal getCurrentPage()
+    @Nullable
+    Terminal getCurrentPage()
     {
-        return m_printing ? m_page : null;
+        synchronized( m_page )
+        {
+            return m_printing ? m_page : null;
+        }
     }
 
-    public boolean startNewPage()
+    boolean startNewPage()
     {
-        synchronized( m_inventory )
+        synchronized( m_page )
         {
             if( !canInputPage() ) return false;
             if( m_printing && !outputPage() ) return false;
@@ -326,49 +307,36 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
         }
     }
 
-    public boolean endCurrentPage()
+    boolean endCurrentPage()
     {
-        synchronized( m_inventory )
+        synchronized( m_page )
         {
-            if( m_printing && outputPage() )
-            {
-                return true;
-            }
-        }
-        return false;
-    }
-
-    public int getInkLevel()
-    {
-        synchronized( m_inventory )
-        {
-            ItemStack inkStack = m_inventory.get( 0 );
-            return isInk( inkStack ) ? inkStack.getCount() : 0;
+            return m_printing && outputPage();
         }
     }
 
-    public int getPaperLevel()
+    int getInkLevel()
+    {
+        ItemStack inkStack = m_inventory.get( 0 );
+        return isInk( inkStack ) ? inkStack.getCount() : 0;
+    }
+
+    int getPaperLevel()
     {
         int count = 0;
-        synchronized( m_inventory )
+        for( int i = 1; i < 7; i++ )
         {
-            for( int i = 1; i < 7; i++ )
-            {
-                ItemStack paperStack = m_inventory.get( i );
-                if( !paperStack.isEmpty() && isPaper( paperStack ) )
-                {
-                    count += paperStack.getCount();
-                }
-            }
+            ItemStack paperStack = m_inventory.get( i );
+            if( isPaper( paperStack ) ) count += paperStack.getCount();
         }
         return count;
     }
 
-    public void setPageTitle( String title )
+    void setPageTitle( String title )
     {
-        if( m_printing )
+        synchronized( m_page )
         {
-            m_pageTitle = title;
+            if( m_printing ) m_pageTitle = title;
         }
     }
 
@@ -385,145 +353,126 @@ public class TilePrinter extends TilePeripheralBase implements DefaultSidedInven
 
     private boolean canInputPage()
     {
-        synchronized( m_inventory )
-        {
-            ItemStack inkStack = m_inventory.get( 0 );
-            return !inkStack.isEmpty() && isInk( inkStack ) && getPaperLevel() > 0;
-        }
+        ItemStack inkStack = m_inventory.get( 0 );
+        return !inkStack.isEmpty() && isInk( inkStack ) && getPaperLevel() > 0;
     }
 
     private boolean inputPage()
     {
-        synchronized( m_inventory )
+        ItemStack inkStack = m_inventory.get( 0 );
+        if( !isInk( inkStack ) ) return false;
+
+        for( int i = 1; i < 7; i++ )
         {
-            ItemStack inkStack = m_inventory.get( 0 );
-            if( !isInk( inkStack ) ) return false;
+            ItemStack paperStack = m_inventory.get( i );
+            if( paperStack.isEmpty() || !isPaper( paperStack ) ) continue;
 
-            for( int i = 1; i < 7; i++ )
+            // Setup the new page
+            int colour = inkStack.getItemDamage();
+            m_page.setTextColour( colour >= 0 && colour < 16 ? 15 - colour : 15 );
+
+            m_page.clear();
+            if( paperStack.getItem() instanceof ItemPrintout )
             {
-                ItemStack paperStack = m_inventory.get( i );
-                if( !paperStack.isEmpty() && isPaper( paperStack ) )
+                m_pageTitle = ItemPrintout.getTitle( paperStack );
+                String[] text = ItemPrintout.getText( paperStack );
+                String[] textColour = ItemPrintout.getColours( paperStack );
+                for( int y = 0; y < m_page.getHeight(); y++ )
                 {
-                    // Setup the new page
-                    int colour = inkStack.getItemDamage();
-                    m_page.setTextColour( colour >= 0 && colour < 16 ? 15 - colour : 15 );
-
-                    m_page.clear();
-                    if( paperStack.getItem() instanceof ItemPrintout )
-                    {
-                        m_pageTitle = ItemPrintout.getTitle( paperStack );
-                        String[] text = ItemPrintout.getText( paperStack );
-                        String[] textColour = ItemPrintout.getColours( paperStack );
-                        for( int y = 0; y < m_page.getHeight(); y++ )
-                        {
-                            m_page.setLine( y, text[y], textColour[y], "" );
-                        }
-                    }
-                    else
-                    {
-                        m_pageTitle = "";
-                    }
-                    m_page.setCursorPos( 0, 0 );
-
-                    // Decrement ink
-                    inkStack.shrink( 1 );
-                    if( inkStack.isEmpty() ) m_inventory.set( 0, ItemStack.EMPTY );
-
-                    // Decrement paper
-                    paperStack.shrink( 1 );
-                    if( paperStack.isEmpty() )
-                    {
-                        m_inventory.set( i, ItemStack.EMPTY );
-                        updateAnim();
-                    }
-
-                    markDirty();
-                    m_printing = true;
-                    return true;
+                    m_page.setLine( y, text[y], textColour[y], "" );
                 }
             }
-            return false;
+            else
+            {
+                m_pageTitle = "";
+            }
+            m_page.setCursorPos( 0, 0 );
+
+            // Decrement ink
+            inkStack.shrink( 1 );
+            if( inkStack.isEmpty() ) m_inventory.set( 0, ItemStack.EMPTY );
+
+            // Decrement paper
+            paperStack.shrink( 1 );
+            if( paperStack.isEmpty() )
+            {
+                m_inventory.set( i, ItemStack.EMPTY );
+                updateAnim();
+            }
+
+            markDirty();
+            m_printing = true;
+            return true;
         }
+        return false;
     }
 
     private boolean outputPage()
     {
-        synchronized( m_page )
+        int height = m_page.getHeight();
+        String[] lines = new String[height];
+        String[] colours = new String[height];
+        for( int i = 0; i < height; i++ )
         {
-            int height = m_page.getHeight();
-            String[] lines = new String[height];
-            String[] colours = new String[height];
-            for( int i = 0; i < height; i++ )
-            {
-                lines[i] = m_page.getLine( i ).toString();
-                colours[i] = m_page.getTextColourLine( i ).toString();
-            }
-
-            ItemStack stack = ItemPrintout.createSingleFromTitleAndText( m_pageTitle, lines, colours );
-            synchronized( m_inventory )
-            {
-                for( int slot : bottomSlots )
-                {
-                    if( m_inventory.get( slot ).isEmpty() )
-                    {
-                        setInventorySlotContents( slot, stack );
-                        m_printing = false;
-                        return true;
-                    }
-                }
-            }
-            return false;
+            lines[i] = m_page.getLine( i ).toString();
+            colours[i] = m_page.getTextColourLine( i ).toString();
         }
+
+        ItemStack stack = ItemPrintout.createSingleFromTitleAndText( m_pageTitle, lines, colours );
+        for( int slot : BOTTOM_SLOTS )
+        {
+            if( m_inventory.get( slot ).isEmpty() )
+            {
+                setInventorySlotContents( slot, stack );
+                m_printing = false;
+                return true;
+            }
+        }
+        return false;
     }
 
     private void ejectContents()
     {
-        synchronized( m_inventory )
+        for( int i = 0; i < 13; i++ )
         {
-            for( int i = 0; i < 13; i++ )
+            ItemStack stack = m_inventory.get( i );
+            if( !stack.isEmpty() )
             {
-                ItemStack stack = m_inventory.get( i );
-                if( !stack.isEmpty() )
-                {
-                    // Remove the stack from the inventory
-                    setInventorySlotContents( i, ItemStack.EMPTY );
+                // Remove the stack from the inventory
+                setInventorySlotContents( i, ItemStack.EMPTY );
 
-                    // Spawn the item in the world
-                    BlockPos pos = getPos();
-                    double x = pos.getX() + 0.5;
-                    double y = pos.getY() + 0.75;
-                    double z = pos.getZ() + 0.5;
-                    WorldUtil.dropItemStack( stack, getWorld(), x, y, z );
-                }
+                // Spawn the item in the world
+                BlockPos pos = getPos();
+                double x = pos.getX() + 0.5;
+                double y = pos.getY() + 0.75;
+                double z = pos.getZ() + 0.5;
+                WorldUtil.dropItemStack( stack, getWorld(), x, y, z );
             }
         }
     }
 
     private void updateAnim()
     {
-        synchronized( m_inventory )
+        int anim = 0;
+        for( int i = 1; i < 7; i++ )
         {
-            int anim = 0;
-            for( int i = 1; i < 7; i++ )
+            ItemStack stack = m_inventory.get( i );
+            if( !stack.isEmpty() && isPaper( stack ) )
             {
-                ItemStack stack = m_inventory.get( i );
-                if( !stack.isEmpty() && isPaper( stack ) )
-                {
-                    anim += 1;
-                    break;
-                }
+                anim += 1;
+                break;
             }
-            for( int i = 7; i < 13; i++ )
-            {
-                ItemStack stack = m_inventory.get( i );
-                if( !stack.isEmpty() && isPaper( stack ) )
-                {
-                    anim += 2;
-                    break;
-                }
-            }
-            setAnim( anim );
         }
+        for( int i = 7; i < 13; i++ )
+        {
+            ItemStack stack = m_inventory.get( i );
+            if( !stack.isEmpty() && isPaper( stack ) )
+            {
+                anim += 2;
+                break;
+            }
+        }
+        setAnim( anim );
     }
 
     @Override

src/main/java/dan200/computercraft/shared/peripheral/speaker/SpeakerPeripheral.java

@@ -23,8 +23,8 @@ import net.minecraft.world.World;
 import javax.annotation.Nonnull;
 import java.util.concurrent.atomic.AtomicInteger;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.getString;
-import static dan200.computercraft.core.apis.ArgumentHelper.optReal;
+import static dan200.computercraft.api.lua.ArgumentHelper.getString;
+import static dan200.computercraft.api.lua.ArgumentHelper.optFiniteDouble;
 
 public abstract class SpeakerPeripheral implements IPeripheral
 {
@@ -84,8 +84,8 @@ public abstract class SpeakerPeripheral implements IPeripheral
             case 0: // playSound
             {
                 String name = getString( args, 0 );
-                float volume = (float) optReal( args, 1, 1.0 );
-                float pitch = (float) optReal( args, 2, 1.0 );
+                float volume = (float) optFiniteDouble( args, 1, 1.0 );
+                float pitch = (float) optFiniteDouble( args, 2, 1.0 );
 
                 return new Object[] { playSound( context, name, volume, pitch, false ) };
             }
@@ -102,8 +102,8 @@ public abstract class SpeakerPeripheral implements IPeripheral
     private synchronized Object[] playNote( Object[] arguments, ILuaContext context ) throws LuaException
     {
         String name = getString( arguments, 0 );
-        float volume = (float) optReal( arguments, 1, 1.0 );
-        float pitch = (float) optReal( arguments, 2, 1.0 );
+        float volume = (float) optFiniteDouble( arguments, 1, 1.0 );
+        float pitch = (float) optFiniteDouble( arguments, 2, 1.0 );
 
         String noteName = "block.note." + name;
 

src/main/java/dan200/computercraft/shared/turtle/FurnaceRefuelHandler.java

@@ -30,9 +30,13 @@ public final class FurnaceRefuelHandler implements TurtleRefuelEvent.Handler
     @Override
     public int refuel( @Nonnull ITurtleAccess turtle, @Nonnull ItemStack currentStack, int slot, int limit )
     {
-        ItemStack stack = turtle.getItemHandler().extractItem( slot, limit, false );
-        int fuelToGive = getFuelPerItem( stack ) * stack.getCount();
+        int fuelSpaceLeft = turtle.getFuelLimit() - turtle.getFuelLevel();
+        int fuelPerItem = getFuelPerItem( turtle.getItemHandler().getStackInSlot( slot ) );
+        int fuelItemLimit = (int) Math.ceil( fuelSpaceLeft / (double) fuelPerItem );
+        if( limit > fuelItemLimit ) limit = fuelItemLimit;
 
+        ItemStack stack = turtle.getItemHandler().extractItem( slot, limit, false );
+        int fuelToGive = fuelPerItem * stack.getCount();
         // Store the replacement item in the inventory
         ItemStack replacementStack = stack.getItem().getContainerItem( stack );
         if( !replacementStack.isEmpty() )

src/main/java/dan200/computercraft/shared/turtle/apis/TurtleAPI.java

@@ -27,7 +27,7 @@ import javax.annotation.Nullable;
 import java.util.HashMap;
 import java.util.Map;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.*;
+import static dan200.computercraft.api.lua.ArgumentHelper.*;
 
 public class TurtleAPI implements ILuaAPI
 {
@@ -334,9 +334,11 @@ public class TurtleAPI implements ILuaAPI
                 return tryCommand( context, new TurtleInspectCommand( InteractDirection.Up ) );
             case 40: // inspectDown
                 return tryCommand( context, new TurtleInspectCommand( InteractDirection.Down ) );
-            case 41:
+            case 41: // getItemDetail
             {
-                // getItemDetail
+                // FIXME: There's a race condition here if the stack is being modified (mutating NBT, etc...)
+                //  on another thread. The obvious solution is to move this into a command, but some programs rely
+                //  on this having a 0-tick delay.
                 int slot = parseOptionalSlotNumber( args, 0, m_turtle.getSelectedSlot() );
                 ItemStack stack = m_turtle.getInventory().getStackInSlot( slot );
                 if( stack.isEmpty() ) return new Object[] { null };

src/main/java/dan200/computercraft/shared/turtle/blocks/BlockTurtle.java

@@ -58,7 +58,7 @@ public class BlockTurtle extends BlockComputerBase
     @Deprecated
     public EnumBlockRenderType getRenderType( IBlockState state )
     {
-        return EnumBlockRenderType.INVISIBLE;
+        return EnumBlockRenderType.ENTITYBLOCK_ANIMATED;
     }
 
     @Override
@@ -218,7 +218,7 @@ public class BlockTurtle extends BlockComputerBase
     @Deprecated
     public float getExplosionResistance( Entity exploder )
     {
-        if( getFamily() == ComputerFamily.Advanced && (exploder instanceof EntityLivingBase || exploder instanceof EntityFireball) )
+        if( getFamily() == ComputerFamily.Advanced || exploder instanceof EntityLivingBase || exploder instanceof EntityFireball )
         {
             return 2000;
         }

src/main/java/dan200/computercraft/shared/turtle/blocks/TileTurtle.java

@@ -43,19 +43,16 @@ import net.minecraftforge.items.wrapper.InvWrapper;
 
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
+import java.util.Collections;
 
 import static net.minecraftforge.items.CapabilityItemHandler.ITEM_HANDLER_CAPABILITY;
 
 public class TileTurtle extends TileComputerBase implements ITurtleTile, DefaultInventory
 {
-    // Statics
-
     public static final int INVENTORY_SIZE = 16;
     public static final int INVENTORY_WIDTH = 4;
     public static final int INVENTORY_HEIGHT = 4;
 
-    // Members
-
     enum MoveState
     {
         NOT_MOVED,
@@ -63,12 +60,12 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
         MOVED
     }
 
-    private NonNullList<ItemStack> m_inventory;
-    private NonNullList<ItemStack> m_previousInventory;
+    private final NonNullList<ItemStack> m_inventory = NonNullList.withSize( INVENTORY_SIZE, ItemStack.EMPTY );
+    private final NonNullList<ItemStack> m_previousInventory = NonNullList.withSize( INVENTORY_SIZE, ItemStack.EMPTY );
     private final IItemHandlerModifiable m_itemHandler = new InvWrapper( this );
-    private boolean m_inventoryChanged;
-    private TurtleBrain m_brain;
-    private MoveState m_moveState;
+    private boolean m_inventoryChanged = false;
+    private TurtleBrain m_brain = new TurtleBrain( this );
+    private MoveState m_moveState = MoveState.NOT_MOVED;
     private ComputerFamily m_family;
 
     public TileTurtle()
@@ -78,15 +75,10 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
 
     public TileTurtle( ComputerFamily family )
     {
-        m_inventory = NonNullList.withSize( INVENTORY_SIZE, ItemStack.EMPTY );
-        m_previousInventory = NonNullList.withSize( INVENTORY_SIZE, ItemStack.EMPTY );
-        m_inventoryChanged = false;
-        m_brain = new TurtleBrain( this );
-        m_moveState = MoveState.NOT_MOVED;
         m_family = family;
     }
 
-    public boolean hasMoved()
+    private boolean hasMoved()
     {
         return m_moveState == MoveState.MOVED;
     }
@@ -95,7 +87,7 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
     protected ServerComputer createComputer( int instanceID, int id )
     {
         ServerComputer computer = new ServerComputer(
-            getWorld(), id, m_label, instanceID, getFamily(),
+            getWorld(), id, label, instanceID, getFamily(),
             ComputerCraft.terminalWidth_turtle, ComputerCraft.terminalHeight_turtle
         );
         computer.setPosition( getPos() );
@@ -224,18 +216,15 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
     {
         super.update();
         m_brain.update();
-        synchronized( m_inventory )
+        if( !getWorld().isRemote && m_inventoryChanged )
         {
-            if( !getWorld().isRemote && m_inventoryChanged )
-            {
-                ServerComputer computer = getServerComputer();
-                if( computer != null ) computer.queueEvent( "turtle_inventory" );
+            ServerComputer computer = getServerComputer();
+            if( computer != null ) computer.queueEvent( "turtle_inventory" );
 
-                m_inventoryChanged = false;
-                for( int n = 0; n < getSizeInventory(); n++ )
-                {
-                    m_previousInventory.set( n, InventoryUtil.copyItem( getStackInSlot( n ) ) );
-                }
+            m_inventoryChanged = false;
+            for( int n = 0; n < getSizeInventory(); n++ )
+            {
+                m_previousInventory.set( n, getStackInSlot( n ).copy() );
             }
         }
     }
@@ -270,8 +259,8 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
 
         // Read inventory
         NBTTagList nbttaglist = nbt.getTagList( "Items", Constants.NBT.TAG_COMPOUND );
-        m_inventory = NonNullList.withSize( INVENTORY_SIZE, ItemStack.EMPTY );
-        m_previousInventory = NonNullList.withSize( INVENTORY_SIZE, ItemStack.EMPTY );
+        m_inventory.clear();
+        m_previousInventory.clear();
         for( int i = 0; i < nbttaglist.tagCount(); i++ )
         {
             NBTTagCompound tag = nbttaglist.getCompoundTagAt( i );
@@ -279,7 +268,7 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
             if( slot < getSizeInventory() )
             {
                 m_inventory.set( slot, new ItemStack( tag ) );
-                m_previousInventory.set( slot, InventoryUtil.copyItem( m_inventory.get( slot ) ) );
+                m_previousInventory.set( slot, m_inventory.get( slot ).copy() );
             }
         }
 
@@ -382,7 +371,7 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
         return m_family;
     }
 
-    public void setOwningPlayer( GameProfile player )
+    void setOwningPlayer( GameProfile player )
     {
         m_brain.setOwningPlayer( player );
         markDirty();
@@ -410,109 +399,76 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
     @Override
     public ItemStack getStackInSlot( int slot )
     {
-        if( slot >= 0 && slot < INVENTORY_SIZE )
-        {
-            synchronized( m_inventory )
-            {
-                return m_inventory.get( slot );
-            }
-        }
-        return ItemStack.EMPTY;
+        return slot >= 0 && slot < INVENTORY_SIZE ? m_inventory.get( slot ) : ItemStack.EMPTY;
     }
 
     @Nonnull
     @Override
     public ItemStack removeStackFromSlot( int slot )
     {
-        synchronized( m_inventory )
-        {
-            ItemStack result = getStackInSlot( slot );
-            setInventorySlotContents( slot, ItemStack.EMPTY );
-            return result;
-        }
+        ItemStack result = getStackInSlot( slot );
+        setInventorySlotContents( slot, ItemStack.EMPTY );
+        return result;
     }
 
     @Nonnull
     @Override
     public ItemStack decrStackSize( int slot, int count )
     {
-        if( count == 0 )
+        if( count == 0 ) return ItemStack.EMPTY;
+
+        ItemStack stack = getStackInSlot( slot );
+        if( stack.isEmpty() ) return ItemStack.EMPTY;
+
+        if( stack.getCount() <= count )
         {
-            return ItemStack.EMPTY;
+            setInventorySlotContents( slot, ItemStack.EMPTY );
+            return stack;
         }
 
-        synchronized( m_inventory )
-        {
-            ItemStack stack = getStackInSlot( slot );
-            if( stack.isEmpty() )
-            {
-                return ItemStack.EMPTY;
-            }
-
-            if( stack.getCount() <= count )
-            {
-                setInventorySlotContents( slot, ItemStack.EMPTY );
-                return stack;
-            }
-
-            ItemStack part = stack.splitStack( count );
-            onInventoryDefinitelyChanged();
-            return part;
-        }
+        ItemStack part = stack.splitStack( count );
+        onInventoryDefinitelyChanged();
+        return part;
     }
 
     @Override
     public void setInventorySlotContents( int i, @Nonnull ItemStack stack )
     {
-        if( i >= 0 && i < INVENTORY_SIZE )
+        if( i >= 0 && i < INVENTORY_SIZE && !InventoryUtil.areItemsEqual( stack, m_inventory.get( i ) ) )
         {
-            synchronized( m_inventory )
-            {
-                if( !InventoryUtil.areItemsEqual( stack, m_inventory.get( i ) ) )
-                {
-                    m_inventory.set( i, stack );
-                    onInventoryDefinitelyChanged();
-                }
-            }
+            m_inventory.set( i, stack );
+            onInventoryDefinitelyChanged();
         }
     }
 
     @Override
     public void clear()
     {
-        synchronized( m_inventory )
+        boolean changed = false;
+        for( int i = 0; i < INVENTORY_SIZE; i++ )
         {
-            boolean changed = false;
-            for( int i = 0; i < INVENTORY_SIZE; i++ )
+            if( !m_inventory.get( i ).isEmpty() )
             {
-                if( !m_inventory.get( i ).isEmpty() )
-                {
-                    m_inventory.set( i, ItemStack.EMPTY );
-                    changed = true;
-                }
-            }
-            if( changed )
-            {
-                onInventoryDefinitelyChanged();
+                m_inventory.set( i, ItemStack.EMPTY );
+                changed = true;
             }
         }
+
+        if( changed ) onInventoryDefinitelyChanged();
     }
 
     @Override
     public void markDirty()
     {
         super.markDirty();
-        synchronized( m_inventory )
+        if( !m_inventoryChanged )
         {
-            if( !m_inventoryChanged )
+            for( int n = 0; n < getSizeInventory(); n++ )
             {
-                for( int n = 0; n < getSizeInventory(); n++ )
+                if( !ItemStack.areItemStacksEqual( getStackInSlot( n ), m_previousInventory.get( n ) ) )
                 {
-                    if( !ItemStack.areItemStacksEqual( getStackInSlot( n ), m_previousInventory.get( n ) ) )
-                    {
-                        m_inventoryChanged = true;
-                        break;
-                    }
+                    m_inventoryChanged = true;
+                    break;
                 }
             }
         }
@@ -574,8 +530,8 @@ public class TileTurtle extends TileComputerBase implements ITurtleTile, Default
     public void transferStateFrom( TileTurtle copy )
     {
         super.transferStateFrom( copy );
-        m_inventory = copy.m_inventory;
-        m_previousInventory = copy.m_previousInventory;
+        Collections.copy( m_inventory, copy.m_inventory );
+        Collections.copy( m_previousInventory, copy.m_previousInventory );
         m_inventoryChanged = copy.m_inventoryChanged;
         m_brain = copy.m_brain;
         m_brain.setOwner( this );

src/main/java/dan200/computercraft/shared/turtle/core/TurtleBrain.java

@@ -20,10 +20,7 @@ import dan200.computercraft.shared.computer.blocks.TileComputerBase;
 import dan200.computercraft.shared.computer.core.ComputerFamily;
 import dan200.computercraft.shared.computer.core.ServerComputer;
 import dan200.computercraft.shared.turtle.blocks.TileTurtle;
-import dan200.computercraft.shared.util.Colour;
-import dan200.computercraft.shared.util.ColourUtils;
-import dan200.computercraft.shared.util.Holiday;
-import dan200.computercraft.shared.util.HolidayUtil;
+import dan200.computercraft.shared.util.*;
 import net.minecraft.block.Block;
 import net.minecraft.entity.Entity;
 import net.minecraft.entity.MoverType;
@@ -40,6 +37,7 @@ import net.minecraft.util.math.Vec3d;
 import net.minecraft.world.World;
 import net.minecraftforge.common.util.Constants;
 import net.minecraftforge.items.IItemHandlerModifiable;
+import net.minecraftforge.items.wrapper.InvWrapper;
 
 import javax.annotation.Nonnull;
 import java.util.*;
@@ -53,6 +51,9 @@ public class TurtleBrain implements ITurtleAccess
     private ComputerProxy m_proxy;
     private GameProfile m_owningPlayer;
 
+    private final IInventory m_inventory = (InventoryDelegate) () -> m_owner;
+    private final IItemHandlerModifiable m_inventoryWrapper = new InvWrapper( m_inventory );
+
     private Queue<TurtleCommandQueueEntry> m_commandQueue = new ArrayDeque<>();
     private int m_commandsIssued = 0;
 
@@ -531,14 +532,14 @@ public class TurtleBrain implements ITurtleAccess
     @Override
     public IInventory getInventory()
     {
-        return m_owner;
+        return m_inventory;
     }
 
     @Nonnull
     @Override
     public IItemHandlerModifiable getItemHandler()
     {
-        return m_owner.getItemHandler();
+        return m_inventoryWrapper;
     }
 
     @Override

src/main/java/dan200/computercraft/shared/turtle/core/TurtlePlayer.java

@@ -8,6 +8,7 @@ package dan200.computercraft.shared.turtle.core;
 
 import com.mojang.authlib.GameProfile;
 import dan200.computercraft.api.turtle.ITurtleAccess;
+import dan200.computercraft.shared.util.FakeNetHandler;
 import dan200.computercraft.shared.util.InventoryUtil;
 import dan200.computercraft.shared.util.WorldUtil;
 import net.minecraft.entity.Entity;
@@ -37,7 +38,7 @@ public class TurtlePlayer extends FakePlayer
     );
 
     /**
-     * Construct a TurtlePlayer which exists in the world
+     * Construct a TurtlePlayer which exists in the world.
      *
      * @param world The world the player exists in
      * @deprecated This is required by {@link Entity}.
@@ -46,11 +47,13 @@ public class TurtlePlayer extends FakePlayer
     public TurtlePlayer( World world )
     {
         super( (WorldServer) world, DEFAULT_PROFILE );
+        connection = new FakeNetHandler( this );
     }
 
     private TurtlePlayer( ITurtleAccess turtle )
     {
         super( (WorldServer) turtle.getWorld(), getProfile( turtle.getOwningPlayer() ) );
+        connection = new FakeNetHandler( this );
         setState( turtle );
     }
 

src/main/java/dan200/computercraft/shared/turtle/items/ItemTurtleBase.java

@@ -48,13 +48,11 @@ public abstract class ItemTurtleBase extends ItemComputerBase implements ITurtle
         ItemStack normalStack = TurtleItemFactory.create( -1, null, -1, family, null, null, 0, null );
         if( !normalStack.isEmpty() && normalStack.getItem() == this ) list.add( normalStack );
 
-        for( ITurtleUpgrade upgrade : TurtleUpgrades.getVanillaUpgrades() )
-        {
-            if( !TurtleUpgrades.suitableForFamily( family, upgrade ) ) continue;
-
-            ItemStack stack = TurtleItemFactory.create( -1, null, -1, family, null, upgrade, 0, null );
-            if( !stack.isEmpty() && stack.getItem() == this ) list.add( stack );
-        }
+        TurtleUpgrades.getVanillaUpgrades()
+            .filter( x -> TurtleUpgrades.suitableForFamily( family, x ) )
+            .map( x -> TurtleItemFactory.create( -1, null, -1, family, null, x, 0, null ) )
+            .filter( x -> !x.isEmpty() && x.getItem() == this )
+            .forEach( list::add );
     }
 
     @Nonnull

src/main/java/dan200/computercraft/shared/turtle/upgrades/CraftingTablePeripheral.java

@@ -15,7 +15,7 @@ import dan200.computercraft.shared.turtle.core.TurtleCraftCommand;
 
 import javax.annotation.Nonnull;
 
-import static dan200.computercraft.core.apis.ArgumentHelper.optInt;
+import static dan200.computercraft.api.lua.ArgumentHelper.optInt;
 
 public class CraftingTablePeripheral implements IPeripheral
 {

src/main/java/dan200/computercraft/shared/turtle/upgrades/TurtleAxe.java

@@ -7,6 +7,7 @@
 package dan200.computercraft.shared.turtle.upgrades;
 
 import net.minecraft.item.Item;
+import net.minecraft.item.ItemStack;
 import net.minecraft.util.ResourceLocation;
 
 public class TurtleAxe extends TurtleTool
@@ -21,6 +22,11 @@ public class TurtleAxe extends TurtleTool
         super( id, legacyId, item );
     }
 
+    public TurtleAxe( ResourceLocation id, ItemStack craftItem, ItemStack toolItem )
+    {
+        super( id, craftItem, toolItem );
+    }
+
     @Override
     protected float getDamageMultiplier()
     {

src/main/java/dan200/computercraft/shared/turtle/upgrades/TurtleHoe.java

@@ -35,6 +35,11 @@ public class TurtleHoe extends TurtleTool
         super( id, legacyId, item );
     }
 
+    public TurtleHoe( ResourceLocation id, ItemStack craftItem, ItemStack toolItem )
+    {
+        super( id, craftItem, toolItem );
+    }
+
     @Override
     protected boolean canBreakBlock( IBlockState state, World world, BlockPos pos, TurtlePlayer player )
     {

src/main/java/dan200/computercraft/shared/turtle/upgrades/TurtleShovel.java

@@ -35,6 +35,11 @@ public class TurtleShovel extends TurtleTool
         super( id, legacyId, item );
     }
 
+    public TurtleShovel( ResourceLocation id, ItemStack craftItem, ItemStack toolItem )
+    {
+        super( id, craftItem, toolItem );
+    }
+
     @Override
     protected boolean canBreakBlock( IBlockState state, World world, BlockPos pos, TurtlePlayer player )
     {

src/main/java/dan200/computercraft/shared/turtle/upgrades/TurtleSword.java

@@ -10,6 +10,7 @@ import dan200.computercraft.shared.turtle.core.TurtlePlayer;
 import net.minecraft.block.material.Material;
 import net.minecraft.block.state.IBlockState;
 import net.minecraft.item.Item;
+import net.minecraft.item.ItemStack;
 import net.minecraft.util.ResourceLocation;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.world.World;
@@ -26,6 +27,11 @@ public class TurtleSword extends TurtleTool
         super( id, legacyId, item );
     }
 
+    public TurtleSword( ResourceLocation id, ItemStack craftItem, ItemStack toolItem )
+    {
+        super( id, craftItem, toolItem );
+    }
+
     @Override
     protected boolean canBreakBlock( IBlockState state, World world, BlockPos pos, TurtlePlayer player )
     {

src/main/java/dan200/computercraft/shared/turtle/upgrades/TurtleTool.java

@@ -62,6 +62,12 @@ public class TurtleTool extends AbstractTurtleUpgrade
         this.item = new ItemStack( item, 1, 0 );
     }
 
+    public TurtleTool( ResourceLocation id, ItemStack craftItem, ItemStack toolItem )
+    {
+        super( id, -1, TurtleUpgradeType.Tool, craftItem );
+        this.item = toolItem;
+    }
+
     @Nonnull
     @Override
     @SideOnly( Side.CLIENT )
@@ -76,7 +82,7 @@ public class TurtleTool extends AbstractTurtleUpgrade
         );
         Minecraft mc = Minecraft.getMinecraft();
         return Pair.of(
-            mc.getRenderItem().getItemModelMesher().getItemModel( item ),
+            mc.getRenderItem().getItemModelMesher().getItemModel( getCraftingItem() ),
             transform
         );
     }
@@ -246,7 +252,7 @@ public class TurtleTool extends AbstractTurtleUpgrade
         boolean canHarvest = state.getBlock().canHarvestBlock( world, blockPosition, turtlePlayer );
         boolean canBreak = state.getBlock().removedByPlayer( state, world, blockPosition, turtlePlayer, canHarvest );
         if( canBreak ) state.getBlock().onPlayerDestroy( world, blockPosition, state );
-        if( canHarvest )
+        if( canHarvest && canBreak )
         {
             state.getBlock().harvestBlock( world, turtlePlayer, blockPosition, state, tile, turtlePlayer.getHeldItemMainhand() );
         }

src/main/java/dan200/computercraft/shared/util/DropConsumer.java

@@ -14,8 +14,6 @@ import net.minecraft.util.math.AxisAlignedBB;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.world.World;
 import net.minecraftforge.event.entity.EntityJoinWorldEvent;
-import net.minecraftforge.event.entity.living.LivingDropsEvent;
-import net.minecraftforge.event.world.BlockEvent;
 import net.minecraftforge.fml.common.Mod;
 import net.minecraftforge.fml.common.eventhandler.EventPriority;
 import net.minecraftforge.fml.common.eventhandler.SubscribeEvent;
@@ -35,7 +33,6 @@ public final class DropConsumer
     private static Function<ItemStack, ItemStack> dropConsumer;
     private static List<ItemStack> remainingDrops;
     private static WeakReference<World> dropWorld;
-    private static BlockPos dropPos;
     private static AxisAlignedBB dropBounds;
     private static WeakReference<Entity> dropEntity;
 
@@ -45,7 +42,6 @@ public final class DropConsumer
         remainingDrops = new ArrayList<>();
         dropEntity = new WeakReference<>( entity );
         dropWorld = new WeakReference<>( entity.world );
-        dropPos = null;
         dropBounds = new AxisAlignedBB( entity.getPosition() ).grow( 2, 2, 2 );
 
         entity.captureDrops = true;
@@ -54,10 +50,9 @@ public final class DropConsumer
     public static void set( World world, BlockPos pos, Function<ItemStack, ItemStack> consumer )
     {
         dropConsumer = consumer;
-        remainingDrops = new ArrayList<>();
+        remainingDrops = new ArrayList<>( 2 );
         dropEntity = null;
         dropWorld = new WeakReference<>( world );
-        dropPos = pos;
         dropBounds = new AxisAlignedBB( pos ).grow( 2, 2, 2 );
     }
 
@@ -83,7 +78,6 @@ public final class DropConsumer
         remainingDrops = null;
         dropEntity = null;
         dropWorld = null;
-        dropPos = null;
         dropBounds = null;
 
         return remainingStacks;
@@ -95,34 +89,7 @@ public final class DropConsumer
         if( !remaining.isEmpty() ) remainingDrops.add( remaining );
     }
 
-    @SubscribeEvent( priority = EventPriority.LOWEST )
-    public static void onEntityLivingDrops( LivingDropsEvent event )
-    {
-        // Capture any mob drops for the current entity
-        if( dropEntity != null && event.getEntity() == dropEntity.get() )
-        {
-            List<EntityItem> drops = event.getDrops();
-            for( EntityItem entityItem : drops ) handleDrops( entityItem.getItem() );
-            drops.clear();
-        }
-    }
-
-    @SubscribeEvent( priority = EventPriority.LOWEST )
-    public static void onHarvestDrops( BlockEvent.HarvestDropsEvent event )
-    {
-        // Capture block drops for the current entity
-        if( dropWorld != null && dropWorld.get() == event.getWorld()
-            && dropPos != null && dropPos.equals( event.getPos() ) )
-        {
-            for( ItemStack item : event.getDrops() )
-            {
-                if( event.getWorld().rand.nextFloat() < event.getDropChance() ) handleDrops( item );
-            }
-            event.getDrops().clear();
-        }
-    }
-
-    @SubscribeEvent( priority = EventPriority.LOWEST )
+    @SubscribeEvent( priority = EventPriority.HIGHEST )
     public static void onEntitySpawn( EntityJoinWorldEvent event )
     {
         // Capture any nearby item spawns

src/main/java/dan200/computercraft/shared/util/FakeNetHandler.java

@@ -0,0 +1,234 @@
+/*
+ * This file is part of ComputerCraft - http://www.computercraft.info
+ * Copyright Daniel Ratcliffe, 2011-2019. Do not distribute without permission.
+ * Send enquiries to dratcliffe@gmail.com
+ */
+
+package dan200.computercraft.shared.util;
+
+import io.netty.channel.Channel;
+import io.netty.channel.ChannelHandlerContext;
+import net.minecraft.network.*;
+import net.minecraft.network.play.client.*;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.util.text.ITextComponent;
+import net.minecraftforge.common.util.FakePlayer;
+
+import javax.annotation.Nonnull;
+import javax.crypto.SecretKey;
+
+public class FakeNetHandler extends NetHandlerPlayServer
+{
+    public static class FakeNetworkManager extends NetworkManager
+    {
+        private INetHandler handler;
+
+        public FakeNetworkManager()
+        {
+            super( EnumPacketDirection.CLIENTBOUND );
+        }
+
+        @Override
+        public void channelActive( ChannelHandlerContext context )
+        {
+        }
+
+        @Override
+        public void setConnectionState( @Nonnull EnumConnectionState state )
+        {
+        }
+
+        @Override
+        public void channelInactive( ChannelHandlerContext context )
+        {
+        }
+
+        @Override
+        public void exceptionCaught( ChannelHandlerContext context, @Nonnull Throwable e )
+        {
+        }
+
+        @Override
+        public void setNetHandler( INetHandler handler )
+        {
+            this.handler = handler;
+        }
+
+        @Override
+        public void processReceivedPackets()
+        {
+        }
+
+        @Override
+        public void closeChannel( @Nonnull ITextComponent channel )
+        {
+        }
+
+        @Override
+        public boolean isLocalChannel()
+        {
+            return false;
+        }
+
+
+        @Override
+        public void enableEncryption( SecretKey key )
+        {
+        }
+
+        @Override
+        public boolean isChannelOpen()
+        {
+            return false;
+        }
+
+        @Nonnull
+        @Override
+        public INetHandler getNetHandler()
+        {
+            return handler;
+        }
+
+        @Nonnull
+        @Override
+        public ITextComponent getExitMessage()
+        {
+            return null;
+        }
+
+        @Override
+        public void disableAutoRead()
+        {
+        }
+
+        @Nonnull
+        @Override
+        public Channel channel()
+        {
+            return null;
+        }
+    }
+
+
+    public FakeNetHandler( FakePlayer player )
+    {
+        this( player.server, player );
+    }
+
+    public FakeNetHandler( MinecraftServer server, FakePlayer player )
+    {
+        super( server, new FakeNetworkManager(), player );
+    }
+
+    @Override
+    public void processInput( CPacketInput packet )
+    {
+    }
+
+    @Override
+    public void processPlayer( CPacketPlayer packet )
+    {
+    }
+
+    @Override
+    public void setPlayerLocation( double x, double y, double z, float yaw, float pitch )
+    {
+    }
+
+    @Override
+    public void processPlayerDigging( CPacketPlayerDigging packet )
+    {
+    }
+
+    @Override
+    public void onDisconnect( @Nonnull ITextComponent chat )
+    {
+    }
+
+    @Override
+    @SuppressWarnings( "rawtypes" )
+    public void sendPacket( @Nonnull final Packet packet )
+    {
+
+    }
+
+    @Override
+    public void processHeldItemChange( CPacketHeldItemChange packet )
+    {
+    }
+
+    @Override
+    public void processChatMessage( @Nonnull CPacketChatMessage packet )
+    {
+    }
+
+    @Override
+    public void processEntityAction( CPacketEntityAction packet )
+    {
+    }
+
+    @Override
+    public void processUseEntity( CPacketUseEntity packet )
+    {
+    }
+
+    @Override
+    public void processClientStatus( CPacketClientStatus packet )
+    {
+    }
+
+    @Override
+    public void processCloseWindow( @Nonnull CPacketCloseWindow packet )
+    {
+    }
+
+    @Override
+    public void processClickWindow( CPacketClickWindow packet )
+    {
+    }
+
+    @Override
+    public void processEnchantItem( CPacketEnchantItem packet )
+    {
+    }
+
+    @Override
+    public void processCreativeInventoryAction( @Nonnull CPacketCreativeInventoryAction packet )
+    {
+    }
+
+    @Override
+    public void processConfirmTransaction( @Nonnull CPacketConfirmTransaction packet )
+    {
+    }
+
+    @Override
+    public void processUpdateSign( CPacketUpdateSign packet )
+    {
+    }
+
+    @Override
+    public void processKeepAlive( @Nonnull CPacketKeepAlive packet )
+    {
+    }
+
+    @Override
+    public void processPlayerAbilities( CPacketPlayerAbilities packet )
+    {
+    }
+
+    @Override
+    public void processTabComplete( CPacketTabComplete packet )
+    {
+    }
+
+    @Override
+    public void processClientSettings( @Nonnull CPacketClientSettings packet )
+    {
+    }
+
+    @Override
+    public void processCustomPayload( CPacketCustomPayload packetIn )
+    {
+    }
+}