Lua 5.3

もうすぐ出るようです．

Lua 5.3.0 (work1) is now available for testing at
http://www.lua.org/work/lua-5.3.0-work1.tar.gz

All feedback welcome. Thanks.

ただ，変更ログや，互換性のない変更などを読んでも，難しくてワタクシごときじゃ理解できません．．．

8  Incompatibilities with the Previous Version

Here we list the incompatibilities that you may find when moving a program from Lua 5.1 to Lua 5.2. You can avoid some incompatibilities by compiling Lua with appropriate options (see file luaconf.h). However, all these
compatibility options will be removed in the next version of Lua. Similarly, all features marked as deprecated in Lua 5.1 have been removed in Lua 5.2.

8.1  Changes in the Language

   The concept of environment changed. Only Lua functions have environments. To set the environment of a Lua function, use the variable _ENV or the function load.

    C functions no longer have environments. Use an upvalue with a shared table if you need to keep shared state among several C functions. (You may use luaL_setfuncs to open a C library with all functions sharing a common
    upvalue.)

    To manipulate the "environment" of a userdata (which is now called user value), use the new functions lua_getuservalue and lua_setuservalue.
   Lua identifiers cannot use locale-dependent letters.
   Doing a step or a full collection in the garbage collector does not restart the collector if it has been stopped.
   Weak tables with weak keys now perform like ephemeron tables.
   The event tail return in debug hooks was removed. Instead, tail calls generate a special new event, tail call, so that the debugger can know that there will not be a corresponding return event.
   Equality between function values has changed. Now, a function definition may not create a new value; it may reuse some previous value if there is no observable difference to the new function.

8.2  Changes in the Libraries

   Function module is deprecated. It is easy to set up a module with regular Lua code. Modules are not expected to set global variables.
   Functions setfenv and getfenv were removed, because of the changes in environments.
   Function math.log10 is deprecated. Use math.log with 10 as its second argument, instead.
   Function loadstring is deprecated. Use load instead; it now accepts string arguments and are exactly equivalent to loadstring.
   Function table.maxn is deprecated. Write it in Lua if you really need it.
   Function os.execute now returns true when command terminates successfully and nil plus error information otherwise.
   Function unpack was moved into the table library and therefore must be called as table.unpack.
   Character class %z in patterns is deprecated, as now patterns may contain '\0' as a regular character.
   The table package.loaders was renamed package.searchers.
   Lua does not have bytecode verification anymore. So, all functions that load code (load and loadfile) are potentially insecure when loading untrusted binary data. (Actually, those functions were already insecure because of
    flaws in the verification algorithm.) When in doubt, use the mode argument of those functions to restrict them to loading textual chunks.
   The standard paths in the official distribution may change between versions.

8.3  Changes in the API

   Pseudoindex LUA_GLOBALSINDEX was removed. You must get the global environment from the registry (see S:4.5).
   Pseudoindex LUA_ENVIRONINDEX and functions lua_getfenv/lua_setfenv were removed, as C functions no longer have environments.
   Function luaL_register is deprecated. Use luaL_setfuncs so that your module does not create globals. (Modules are not expected to set global variables anymore.)
   The osize argument to the allocation function may not be zero when creating a new block, that is, when ptr is NULL (see lua_Alloc). Use only the test ptr == NULL to check whether the block is new.
   Finalizers (__gc metamethods) for userdata are called in the reverse order that they were marked for finalization, not that they were created (see S:2.5.1). (Most userdata are marked immediately after they are created.)
    Moreover, if the metatable does not have a __gc field when set, the finalizer will not be called, even if it is set later.
   luaL_typerror was removed. Write your own version if you need it.
   Function lua_cpcall is deprecated. You can simply push the function with lua_pushcfunction and call it with lua_pcall.
   Functions lua_equal and lua_lessthan are deprecated. Use the new lua_compare with appropriate options instead.
   Function lua_objlen was renamed lua_rawlen.
   Function lua_load has an extra parameter, mode. Pass NULL to simulate the old behavior.
   Function lua_resume has an extra parameter, from. Pass NULL or the thread doing the call.

とりあえず，FreeBSDでコンパイルできるかどうか試してみます．メーリングリストでは，Linuxのディストリビューションによってかなりソースコンパイル自体ができないようです．

> make freebsd
> ./src/lua
Lua 5.3.0 (work1)  Copyright (C) 1994-2013 Lua.org, PUC-Rio

できちゃった．．．

互換性のない変更じゃなくて，改良点などは次の通りです．意味が分からないのが多いですが，順次試して解読していきます．．．

Changes since Lua 5.1

Here are the main changes introduced in Lua 5.3. The reference manual lists the incompatibilities that had to be introduced.

Main changes

   yieldable pcall and metamethods
   new lexical scheme for globals
   ephemeron tables
   new library for bitwise operations
   light C functions
   emergency garbage collector
   goto statement
   finalizers for tables

Here are the other changes introduced in Lua 5.3:

Language

   no more fenv for threads or functions
   tables honor the __len metamethod
   hex and \z escapes in strings
   support for hexadecimal floats
   order metamethods work for different types
   no more verification of opcode consistency
   hook event "tail return" replaced by "tail call"
   empty statement
   break statement may appear in the middle of a block

Libraries

   arguments for function called through xpcall
   optional 'mode' argument to load and loadfile (to control binary x text)
   optional 'env' argument to load and loadfile (environment for loaded chunk)
   loadlib may load libraries with global names (RTLD_GLOBAL)
   new function package.searchpath
   modules receive their paths when loaded
   optional base in math.log
   optional separator in string.rep
   file:write returns file
   closing a pipe returns exit status
   os.exit may close state
   new metamethods __pairs and __ipairs
   new option 'isrunning' for collectgarbage and lua_gc
   frontier patterns
   \0 in patterns
   new option *L for io.read
   options for io.lines
   debug.getlocal can access function varargs

C API

   main thread predefined in the registry
   new functions lua_absindex, lua_arith, lua_compare, lua_copy, lua_len, lua_rawgetp, lua_rawsetp, lua_upvalueid, lua_upvaluejoin, lua_version.
   new functions luaL_checkversion, luaL_setmetatable, luaL_testudata, luaL_tolstring.
   lua_pushstring and pushlstring return string
   nparams and isvararg available in debug API
   new lua_Unsigned

Implementation

   max constants per function raised to 2^26
   generational mode for garbage collection (experimental)
   NaN trick (experimental)
   internal (immutable) version of ctypes
   simpler implementation for string buffers
   parser uses much less C-stack space (no more auto arrays)

Lua standalone interpreter

   new -E option to avoid environment variables
   handling of non-string error messages