need to convert C func -> closure within core (no stack usage, please..:)
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- Subject: need to convert C func -> closure within core (no stack usage, please..:)
- From: Asko Kauppi <asko.kauppi@...>
- Date: 2005年3月14日 22:31:39 +0200
I'm modifying the 'luaT_gettmbyobj()' function within ltm.c (5.1w4) in
order to provide a couple of metamethod-like functions that are in fact
fixed within the core.
The problem is.. how exactly to do that?
I have the lua_CFunction pointers, of course, but creating a closure
without touching the stack (if I touch the stack, well, BOOOM...) Any
ideas from harder-than-hard core programmers welcome.
-ak
const TValue *luaT_gettmbyobj (lua_State *L, const TValue *o, TMS
event) {
Table *mt;
switch (ttype(o)) {
case LUA_TTABLE:
mt = hvalue(o)->metatable;
break;
case LUA_TUSERDATA:
mt = uvalue(o)->metatable;
break;
default:
#ifdef ENUM_PATCH
if (ttisenum(o)) {
lua_CFunction f= (event==TM_CALL) ? enum_call :
(event==TM_INDEX) ? enum_index :
(event==TM_NEWINDEX) ? enum_newindex : NULL;
if (f)
{
// 'f' is the C Function pointer, but we need to make it a
closure.
//
fprintf( stderr, "*** ENUM CALL NOT IMPLEMENTED RIGHT !!!
***\n" );
lua_pushcclosure( L, f, 0 /*no upvalues*/ ); //
SHOULDN*T BE A PUSH!
fprintf( stderr, "returning %p\n", f );
fprintf( stderr, "tt %d", ttype(L->top-1) );
return L->top-1; // TBD: is this right?
}
}
#endif
mt = NULL;
}
return (mt ? luaH_getstr(mt, G(L)->tmname[event]) : &luaO_nilobject);
}