mirror of
https://github.com/Jermolene/TiddlyWiki5
synced 2024-12-28 19:10:28 +00:00
110 lines
3.5 KiB
Plaintext
110 lines
3.5 KiB
Plaintext
created: 20221007132845007
|
|
modified: 20230724184009153
|
|
tags: Pragmas
|
|
title: Pragma: \procedure
|
|
type: text/vnd.tiddlywiki
|
|
|
|
<<.from-version "5.3.0">> The ''\procedure'' [[pragma|Pragmas]] is used to [[define procedures|Procedure Definitions]]. It is a shortcut syntax for the SetVariableWidget with an implicit ParametersWidget.
|
|
|
|
The usual form allows procedures to span multiple lines:
|
|
|
|
```
|
|
\procedure <procedure-name>(<param-name>[:<param-default-value>],<param-name>[:<param-default-value>]...)
|
|
<multiple-line-definition-text>
|
|
\end [<procedure-name>]
|
|
```
|
|
|
|
Note that the `\end` marker can optionally specify the name of the procedure to which it relates which allows procedure definitions to be nested.
|
|
|
|
There is also a single line form for shorter procedures:
|
|
|
|
```
|
|
\procedure <procedure-name>(<param-name>[:<param-default-value>],<param-name>[:<param-default-value>]...) <single-line-definition-text>
|
|
```
|
|
|
|
The first line of the definition specifies the procedure name and any parameters. Each parameter has a name and, optionally, a default value that is used if no value is supplied on a particular call to the procedure. The lines that follow contain the text of the procedure text (i.e. the snippet represented by the procedure name), until `\end` appears on a line by itself:
|
|
|
|
For example:
|
|
|
|
```
|
|
\procedure sayhi(name:"Bugs Bunny")
|
|
Hi, I'm <<name>>.
|
|
\end
|
|
|
|
<<sayhi "Jeremy">>
|
|
```
|
|
|
|
Alternatively, the entire definition can be presented on a single line without an `\end` marker:
|
|
|
|
```
|
|
\procedure sayhi(name:"Bugs Bunny") Hi, I'm <<name>>.
|
|
```
|
|
|
|
Procedure definitions can be nested by specifying the name of the procedure in the `\end` marker. For example:
|
|
|
|
<<wikitext-example-without-html src:"""\procedure special-button(caption:"Click me")
|
|
\procedure actions()
|
|
<$action-sendmessage $message="tm-notify" $param="HelloThere"/>
|
|
\end actions
|
|
<$button actions=<<actions>>>
|
|
<<caption>>
|
|
</$button>
|
|
\end special-button
|
|
|
|
<<special-button>>
|
|
""">>
|
|
|
|
! Use of Parameters Inside Procedures
|
|
The parameters can be declared inside procedures. The parameters widget is necessary in a procedure if you want to use computed default values. For example:
|
|
|
|
<<wikitext-example-without-html
|
|
src:"""\procedure myproc()
|
|
<$parameters name={{$:/SiteTitle}} desc={{$:/SiteSubtitle}}>
|
|
This is <<name>> demonstrates <<desc>>.
|
|
</$parameters>
|
|
\end
|
|
|
|
<<myproc>>
|
|
""">>
|
|
|
|
!! Caution in Using Positional Parameters
|
|
Procedures are a shortcut syntax for the SetVariableWidget with an implicit ParametersWidget, so generally there is no reason to have multiple parameters widgets within a definition. In the below example when passing `x` to `myproc`, it will also be set to `a`:
|
|
|
|
<<wikitext-example-without-html
|
|
src:"""\procedure myproc(x:10)
|
|
\parameters (a:100, b:200)
|
|
|
|
x=<<x>>, a=<<a>>, b=<<b>>
|
|
\end
|
|
|
|
<<myproc 50>>
|
|
""">>
|
|
|
|
The reason for that result is clearer if we consider an equivalent with explicit parameters widgets.
|
|
|
|
<$macrocall $name=wikitext-example-without-html
|
|
src='<$let myprog="""
|
|
\parameters (x:10)
|
|
\parameters (a:100, b:200)
|
|
|
|
x=<<x>>, a=<<a>>, b=<<b>>
|
|
""">
|
|
<<myprog 50>>
|
|
</$let>'
|
|
/>
|
|
|
|
This is because those two parameters widgets are entirely independent. They are both processed as if the other parameter widget is not there.
|
|
|
|
<<.tip "The positional parameters are only required when using the parameterised transclusion shortcut syntax, and that in other cases it is generally clearer to use named parameters.">>
|
|
|
|
To prevent such situation of above example, pass parameters by name as below.
|
|
|
|
<<wikitext-example-without-html
|
|
src:"""\procedure myproc(x:10)
|
|
\parameters (a:100, b:200)
|
|
|
|
x=<<x>>, a=<<a>>, b=<<b>>
|
|
\end
|
|
|
|
<<myproc x:50>>
|
|
""">> |