On Sat, Sep 26, 2015 at 4:22 PM, Orion Poplawski <or...@cora.nwra.com>
wrote:
> On 09/25/2015 03:04 PM, Hans Hagen wrote:
>
>> On 9/25/2015 4:09 PM, Orion Poplawski wrote:
>>
>>> I'm just starting to take a look how luatex makes use of lua. And it
>>> appears that luatex does not merely use lua, but extends it in various
>>> ways, essentially creating new lua dialect. Is the assessment correct?
>>> Is there any documentation on this?
>>>
>>
>> Indeed we have some more on board. Keep in mind that lua is used as
>> extension language so whenever it's used in an application there can be
>> extensions.
>>
>> Btw, a dialect implies a different language. Adding a couple of
>> functions is not making it a dialect.
>>
>
> You appear to be extending it in at least four areas by adding new
> functions, and replacing some as described below. liolibext is the most
> "entangled" due to duplicating liolib code, lstrlibext also uses some Lua
> internals that are not normally exposed to consumers of Lua (e.g.
> lua_lock). I'm fine with not calling this a new "dialect", but it is
> certainly extended, though modifying popen()/read()/lines() is
> interesting. I'm interested to know if there has been any discussion with
> the Lua maintainers about incorporating any of these changes in Lua proper?
>
> liolibext.c:
> /* This extension only replaces one function: io.popen() and two
> metatable entries: f:read() and f:lines() but unfortunately
> it has to copy quite a bunch of lines from the original liolib.c
> to do so.
> */
>
> llfslibext.c: adds to lfs:
> lua_setfield(L, -2, "isdir");
> lua_pushcfunction(L, file_is_file);
> lua_setfield(L, -2, "isfile");
> lua_pushcfunction(L, read_link);
> lua_setfield(L, -2, "readlink");
> lua_pushcfunction(L, get_short_name);
> lua_setfield(L, -2, "shortname");
>
> loslibext.c:
> lua_getglobal(L, "os");
> lua_pushcfunction(L, ex_sleep);
> lua_setfield(L, -2, "sleep");
> lua_pushliteral(L, OS_PLATTYPE);
> lua_setfield(L, -2, "type");
> lua_pushliteral(L, OS_PLATNAME);
> lua_setfield(L, -2, "name");
> lua_pushcfunction(L, ex_uname);
> lua_setfield(L, -2, "uname");
> #if (! defined (_WIN32)) && (! defined (__SUNOS__))
> lua_pushcfunction(L, os_times);
> lua_setfield(L, -2, "times");
> #endif
> #if ! defined (__SUNOS__)
> lua_pushcfunction(L, os_gettimeofday);
> lua_setfield(L, -2, "gettimeofday");
> #endif
>
> if (!safer) {
> lua_pushcfunction(L, os_setenv);
> lua_setfield(L, -2, "setenv");
> lua_pushcfunction(L, os_exec);
> lua_setfield(L, -2, "exec");
> lua_pushcfunction(L, os_spawn);
> lua_setfield(L, -2, "spawn");
> lua_pushcfunction(L, os_execute);
> lua_setfield(L, -2, "execute");
> lua_pushcfunction(L, os_tmpdir);
> lua_setfield(L, -2, "tmpdir");
> }
>
> lstrlibext.c
> {"utfvalues", str_utfvalues},
> {"utfcharacters", str_utfcharacters},
> {"characters", str_characters},
> {"characterpairs", str_characterpairs},
> {"bytes", str_bytes},
> {"bytepairs", str_bytepairs},
> {"explode", str_split},
> {"dump", str_dump},
>
> Also, is luajit used in the same way, or would it be possible to use a
>>> system installed luajit in building luatex?
>>>
>>
>> The only benefit of luajit is the faster virtual machine. A downside is
>> that there are some limitations in memory cq. stack usage. We use a
>> patch that makes the string hashing faster (we use the normal lua method
>> instead of the luajit one that is optimizied for urls and that can make
>> luajit slower than lua).
>>
>> Becaus eluatex uses lua as extension language it will always be shipped
>> with a specific version (linked in or alongside the binary).
>>
>> Hans
>>
>
> FWIW - Here are some changes I had to make while trying to compile against
> lua 5.3:
>
> Thank you for the patches --- do they also work for luajittex ?
--
luigi
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