Re: Garbage collection

[Vyacheslav Egorov <mraleph@...>]

Lyte _ wrote:
> When I run this the function I added to the metatable does not get 
> called. What am I doing wrong here?

Looks fine. But could you please inform us what Lua version you are 
using. How you check whether __gc metamethod gets called or not. Can is 
it possible that CreateObject leves reference to return value somewhere. 
Could it be that you modified metatable of global environment?
Try inserting some assertions just after luaL_getmetatable (for example 
ASSERT(lua_istable(L, -1))), etc. Also try to provide complete minimal 
example representing your problem. Because the following example works 
fine with Lua 5.1.1:

// begin code
#include "lua.h"
#include "lauxlib.h"
#include <stdio.h>

static int gc_function (lua_State *L) {
 printf("GC!\n");
 return 0;
}

static void registermt(lua_State *L) {
 luaL_newmetatable(L, "LuaBook.gc_event");

 /* set its __gc field */
 lua_pushstring(L, "__gc");
 lua_pushcfunction(L, gc_function);
 lua_settable(L, -3);

 lua_pop(L, 1); /* pop mt */
}

static int create(lua_State *L) {
 lua_newuserdata(L, sizeof(char));
 luaL_getmetatable(L, "LuaBook.gc_event");
 lua_setmetatable(L, -2);
 return 1;
}

int main() {
 lua_State *L = luaL_newstate();
 registermt(L);
 lua_register(L, "create", create); 
 luaL_openlibs(L);
 luaL_dostring(L, "o = create();"                  \
                  "o = nil;"                       \
                  "print 'before collectgarbage';" \
                  "collectgarbage();"                \
                  "print 'after collectgarbage';"); 
 lua_close(L);
 return 0;
}
// end code

--
e.v.e