lua-compat-5.3
Lua-5.3-style APIs for Lua 5.2 and 5.1.
What is it
This is a small module that aims to make it easier to write code in a Lua-5.3-style that is compatible with Lua 5.1, Lua 5.2, and Lua 5.3. This does not make Lua 5.2 (or even Lua 5.1) entirely compatible with Lua 5.3, but it brings the API closer to that of Lua 5.3.
It includes:
- For writing Lua: The Lua module
compat53
, which can be require'd from Lua scripts and run in Lua 5.1, 5.2, and 5.3, including a backport of theutf8
module, the 5.3table
module, and the string packing functions straight from the Lua 5.3 sources. - For writing C: A C header and file which can be linked to your Lua module written in C, providing some functions from the C API of Lua 5.3 that do not exist in Lua 5.2 or 5.1, making it easier to write C code that compiles with all three versions of liblua.
How to use it
Lua module
require("compat53")
compat53
makes changes to your global environment and does not return
a meaningful return value, so the usual idiom of storing the return of
require
in a local variable makes no sense.
When run under Lua 5.3, this module does nothing.
When run under Lua 5.2 or 5.1, it replaces some of your standard
functions and adds new ones to bring your environment closer to that
of Lua 5.3. It also tries to load the backported utf8
, table
, and
string packing modules automatically. If unsuccessful, pure Lua
versions of the new table
functions are used as a fallback, and
Roberto's struct library is tried for string packing.
Lua submodules
local _ENV = require("compat53.module")
if setfenv then setfenv(1, _ENV) end
The compat53.module
module does not modify the global environment,
and so it is safe to use in modules without affecting other Lua files.
It is supposed to be set as the current environment (see above), i.e.
cherry picking individual functions from this module is expressly
not supported!). Not all features are available when using this
module (e.g. yieldable (x)pcall support, string/file methods, etc.),
so it is recommended to use plain require("compat53")
whenever
possible.
C code
There are two ways of adding the C API compatibility functions/macros to your project:
- If
COMPAT53_PREFIX
is not#define
d,compat-5.3.h
#include
scompat-5.3.c
, and all functions are madestatic
. You don't have to compile/link/addcompat-5.3.c
yourself. This is useful for one-file projects. - If
COMPAT53_PREFIX
is#define
d, all exported functions are renamed behind the scenes using this prefix to avoid linker conflicts with other code using this package. This doesn't change the way you call the compatibility functions in your code. You have to compile and linkcompat-5.3.c
to your project yourself. You can change the way the functions are exported using theCOMPAT53_API
macro (e.g. if you need some__declspec
magic). While it is technically possible to use the "lua" prefix (and it looks better in the debugger), this is discouraged because LuaJIT has started to implement its own Lua 5.2+ C API functions, and with the "lua" prefix you'd violate the one-definition rule with recent LuaJIT versions.
What's implemented
Lua
- the
utf8
module backported from the Lua 5.3 sources string.pack
,string.packsize
, andstring.unpack
from the Lua 5.3 sources or from thestruct
module. (struct
is not 100% compatible to Lua 5.3's string packing!) (See here)math.maxinteger
andmath.mininteger
,math.tointeger
,math.type
, andmath.ult
(see here)assert
accepts non-string error messagesipairs
respects__index
metamethodtable.move
table
library respects metamethods
For Lua 5.1 additionally:
load
andloadfile
acceptmode
andenv
parameterstable.pack
andtable.unpack
- string patterns may contain embedded zeros (but see here)
string.rep
acceptssep
argumentstring.format
callstostring
on arguments for%s
math.log
accepts base argumentxpcall
takes additional argumentspcall
andxpcall
can execute functions that yield (see here for a possible problem withcoroutine.running
)pairs
respects__pairs
metamethod (see here)rawlen
(but#
still doesn't respect__len
for tables)package.searchers
as alias forpackage.loaders
package.searchpath
(see here)coroutine
functions dealing with the main coroutine (see here for a possible problem withcoroutine.running
)coroutine.create
accepts functions written in C- return code of
os.execute
(see here) io.write
andfile:write
return file handleio.lines
andfile:lines
accept format arguments (likeio.read
) (see here and here)debug.setmetatable
returns objectdebug.getuservalue
(see here)debug.setuservalue
(see here)
C
lua_KContext
(see here)lua_KFunction
(see here)lua_dump
(extrastrip
parameter, ignored, see here)lua_getextraspace
(limited compatibilitiy, see here)lua_getfield
(return value)lua_geti
andlua_seti
lua_getglobal
(return value)lua_getmetafield
(return value)lua_gettable
(return value)lua_getuservalue
(limited compatibility, see here)lua_setuservalue
(limited compatibility, see here)lua_isinteger
lua_numbertointeger
lua_callk
andlua_pcallk
(limited compatibility, see here)lua_resume
lua_rawget
andlua_rawgeti
(return values)lua_rawgetp
andlua_rawsetp
luaL_requiref
(now checkspackage.loaded
first)lua_rotate
lua_stringtonumber
(see here)
For Lua 5.1 additionally:
LUA_OK
LUA_ERRGCMM
LUA_OP*
macros forlua_arith
andlua_compare
LUA_FILEHANDLE
lua_Unsigned
luaL_Stream
(limited compatibility, see here)lua_absindex
lua_arith
(see here)lua_compare
lua_len
,lua_rawlen
, andluaL_len
lua_load
(mode argument)lua_pushstring
,lua_pushlstring
(return value)lua_copy
lua_pushglobaltable
luaL_testudata
luaL_setfuncs
,luaL_newlibtable
, andluaL_newlib
luaL_setmetatable
luaL_getsubtable
luaL_traceback
luaL_execresult
luaL_fileresult
luaL_loadbufferx
luaL_loadfilex
luaL_checkversion
(with empty body, only to avoid compile errors, see here)luaL_tolstring
luaL_buffinitsize
,luaL_prepbuffsize
, andluaL_pushresultsize
(see here)lua_pushunsigned
,lua_tounsignedx
,lua_tounsigned
,luaL_checkunsigned
,luaL_optunsigned
, ifLUA_COMPAT_APIINTCASTS
is defined.
What's not implemented
- bit operators
- integer division operator
- utf8 escape sequences
- 64 bit integers
coroutine.isyieldable
- Lua 5.1:
_ENV
,goto
, labels, ephemeron tables, etc. Seelua-compat-5.2
for a detailed list. - the following C API functions/macros:
lua_isyieldable
lua_arith
(new operators missing)lua_push(v)fstring
(new formats missing)lua_upvalueid
(5.1)lua_upvaluejoin
(5.1)lua_version
(5.1)lua_yieldk
(5.1)
See also
- For Lua-5.2-style APIs under Lua 5.1, see lua-compat-5.2, which also is the basis for most of the code in this project.
- For Lua-5.1-style APIs under Lua 5.0, see Compat-5.1
Credits
This package contains code written by:
- The Lua Team
- Philipp Janda (@siffiejoe)
- Tomás Guisasola Gorham (@tomasguisasola)
- Hisham Muhammad (@hishamhm)
- Renato Maia (@renatomaia)
- @ThePhD
- @Daurnimator