Re: Wrapping existing FILE *s as Lua file objects

[Mark Edgar <medgar@...>]

Reuben Thomas wrote:
> I can't see a way to do this after looking at liolib.c and googling a 
> bit. It's obviously fairly trivial to extend liolib.c to do it, but a 
> pain as you can't do it with vanilla Lua.
>
> Am I missing something? I don't imagine it's that rare to want to pass a 
> FILE * obtained from somewhere else into a Lua script without 
> re-inventing the liolib wheel...

The ex implementations do this for the io.pipe() function, which returns 
two Lua file objects.

http://lua-users.org/wiki/ExtensionProposal

    FILE **pf = lua_newuserdata(L, sizeof *pf);
    *pf = 0;
    luaL_getmetatable(L, LUA_FILEHANDLE);
    lua_setmetatable(L, -2);
    *pf = /* your FILE* here */

In Lua 5.1, LUA_FILEHANDLE is defined in lualib.h.

					-Mark