CC-Tweaked/doc/reference/feature_compat.md

module: [kind=reference] feature_compat

Lua 5.2/5.3 features in CC: Tweaked

CC: Tweaked is based off of the Cobalt Lua runtime, which uses Lua 5.2. However, Cobalt and CC:T implement additional features from Lua 5.2 and 5.3 (as well as some deprecated 5.0 and 5.1 features). This page lists all of the compatibility for these newer versions.

Lua 5.2

Feature	Supported?	Notes
goto/labels	✔
_ENV	✔
\z escape	✔
\xNN escape	✔
Hex literal fractional/exponent parts	✔
Empty statements	✔
__len metamethod	✔
__ipairs metamethod	❌	Deprecated in Lua 5.3. ipairs uses __len/__index instead.
__pairs metamethod	✔
bit32 library	✔
collectgarbage isrunning, generational, incremental options	❌	collectgarbage does not exist in CC:T.
New load syntax	✔
loadfile mode parameter	✔	Supports both 5.1 and 5.2+ syntax.
Removed loadstring	❌
Removed getfenv, setfenv	🔶	Only supports closures with an _ENV upvalue.
rawlen function	✔
Negative index to select	✔
Removed unpack	❌
Arguments to xpcall	✔
Second return value from coroutine.running	✔
Removed module	✔
package.loaders -> package.searchers	❌
Second argument to loader functions	✔
package.config	✔
package.searchpath	✔
Removed package.seeall	✔
string.dump on functions with upvalues (blanks them out)	❌	string.dump is not supported
string.rep separator	✔
%g match group	❌
Removal of %z match group	❌
Removed table.maxn	❌
table.pack/table.unpack	✔
math.log base argument	✔
Removed math.log10	❌
*L mode to file:read	✔
os.execute exit type + return value	❌	os.execute does not exist in CC:T.
os.exit close argument	❌	os.exit does not exist in CC:T.
istailcall field in debug.getinfo	❌
nparams field in debug.getinfo	✔
isvararg field in debug.getinfo	✔
debug.getlocal negative indices for varargs	❌
debug.getuservalue/debug.setuservalue	❌	Userdata are rarely used in CC:T, so this is not necessary.
debug.upvalueid	✔
debug.upvaluejoin	✔
Tail call hooks	❌
= prefix for chunks	✔
Yield across C boundary	✔
Removal of ambiguity error	✔
Identifiers may no longer use locale-dependent letters	✔
Ephemeron tables	❌
Identical functions may be reused	❌	Removed in Lua 5.4
Generational garbage collector	❌	Cobalt uses the built-in Java garbage collector.

Lua 5.3

Feature	Supported?	Notes
Integer subtype	❌
Bitwise operators/floor division	❌
\u{XXX} escape sequence	✔
utf8 library	✔
removed __ipairs metamethod	✔
coroutine.isyieldable	✔
string.dump strip argument	✔
string.pack/string.unpack/string.packsize	✔
table.move	✔
math.atan2 -> math.atan	🔶	math.atan supports its two argument form.
Removed math.frexp, math.ldexp, math.pow, math.cosh, math.sinh, math.tanh	❌
math.maxinteger/math.mininteger	❌
math.tointeger	❌
math.type	❌
math.ult	❌
Removed bit32 library	❌
Remove * from file:read modes	✔
Metamethods respected in table.*, ipairs	✔

Lua 5.0

Feature	Supported?	Notes
arg table	🔶	Only set in the shell - not used in functions.
string.gfind	✔	Equal to string.gmatch.
table.getn	✔	Equal to #tbl.
table.setn	❌
math.mod	✔	Equal to math.fmod.
table.foreach/table.foreachi	✔
gcinfo	❌	Cobalt uses the built-in Java garbage collector.