Jump to content
  • Advertisement
Sign in to follow this  
Modred

[Lua] Multiple Light Userdata with Metatables

This topic is 2923 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

Hi there,

I'm confused... Whenever I assign a metatable to a light userdata, ALL other, already metatabled lightuserdatas are asigned to the same metatable. If I'm doing the same with tables, every table gets its unique metatable. Please give my example code a try. It basicly creates 3 new userdata and 2 tables and give them unique metatables... but somehow, as said, all light userdatas change their metatable when a single one gets its.


#include <stdio.h>

#ifdef __cplusplus
extern "C"
{
#endif
#include <lua.h>
#include <lualib.h>
#include <lauxlib.h>
#ifdef __cplusplus
}
#endif

int main(int argc, char** argv)
{
char str[512];
lua_State *L = lua_open();
luaL_openlibs(L);

lua_pushlightuserdata(L, (void*)0xff00ff00);
lua_setglobal(L, "one");
lua_getglobal(L, "one");
luaL_newmetatable(L, "_one");
lua_setglobal(L, "_one");
lua_getglobal(L, "_one");
lua_setmetatable(L, -2);

sprintf(str, "print(\"1 Metatable of one: \"..tostring(getmetatable(one)))"); luaL_dostring (L, str);
sprintf(str, "print(\"1 Metatable of two: \"..tostring(getmetatable(two)))"); luaL_dostring (L, str);
sprintf(str, "print(\"1 Metatable of three: \"..tostring(getmetatable(three)))"); luaL_dostring (L, str);
sprintf(str, "print(\"1 Metatable of four: \"..tostring(getmetatable(four)))"); luaL_dostring (L, str);
sprintf(str, "print(\"1 Metatable of five: \"..tostring(getmetatable(five)))"); luaL_dostring (L, str);
printf("\n");

lua_pushlightuserdata(L, (void*)0xcc00cc00);
lua_setglobal(L, "two");
lua_getglobal(L, "two");
lua_newtable(L);
lua_setglobal(L, "_two");
lua_getglobal(L, "_two");
lua_setmetatable(L, -2);

sprintf(str, "print(\"2 Metatable of one: \"..tostring(getmetatable(one)))"); luaL_dostring (L, str);
sprintf(str, "print(\"2 Metatable of two: \"..tostring(getmetatable(two)))"); luaL_dostring (L, str);
sprintf(str, "print(\"2 Metatable of three: \"..tostring(getmetatable(three)))"); luaL_dostring (L, str);
sprintf(str, "print(\"2 Metatable of four: \"..tostring(getmetatable(four)))"); luaL_dostring (L, str);
sprintf(str, "print(\"2 Metatable of five: \"..tostring(getmetatable(five)))"); luaL_dostring (L, str);
printf("\n");

lua_newtable(L);
lua_setglobal(L, "four");
lua_getglobal(L, "four");
lua_newtable(L);
lua_setglobal(L, "_four");
lua_getglobal(L, "_four");
lua_setmetatable(L, -2);

sprintf(str, "print(\"4 Metatable of one: \"..tostring(getmetatable(one)))"); luaL_dostring (L, str);
sprintf(str, "print(\"4 Metatable of two: \"..tostring(getmetatable(two)))"); luaL_dostring (L, str);
sprintf(str, "print(\"4 Metatable of three: \"..tostring(getmetatable(three)))"); luaL_dostring (L, str);
sprintf(str, "print(\"4 Metatable of four: \"..tostring(getmetatable(four)))"); luaL_dostring (L, str);
sprintf(str, "print(\"4 Metatable of five: \"..tostring(getmetatable(five)))"); luaL_dostring (L, str);
printf("\n");

lua_pushlightuserdata(L, (void*)0x88008800);
lua_setglobal(L, "three");
lua_getglobal(L, "three");
lua_newtable(L);
lua_setglobal(L, "_three");
lua_getglobal(L, "_three");
lua_setmetatable(L, -2);

sprintf(str, "print(\"3 Metatable of one: \"..tostring(getmetatable(one)))"); luaL_dostring (L, str);
sprintf(str, "print(\"3 Metatable of two: \"..tostring(getmetatable(two)))"); luaL_dostring (L, str);
sprintf(str, "print(\"3 Metatable of three: \"..tostring(getmetatable(three)))"); luaL_dostring (L, str);
sprintf(str, "print(\"3 Metatable of four: \"..tostring(getmetatable(four)))"); luaL_dostring (L, str);
sprintf(str, "print(\"3 Metatable of five: \"..tostring(getmetatable(five)))"); luaL_dostring (L, str);
printf("\n");

lua_newtable(L);
lua_setglobal(L, "five");
lua_getglobal(L, "five");
lua_newtable(L);
lua_setglobal(L, "_five");
lua_getglobal(L, "_five");
lua_setmetatable(L, -2);

sprintf(str, "print(\"5 Metatable of one: \"..tostring(getmetatable(one)))"); luaL_dostring (L, str);
sprintf(str, "print(\"5 Metatable of two: \"..tostring(getmetatable(two)))"); luaL_dostring (L, str);
sprintf(str, "print(\"5 Metatable of three: \"..tostring(getmetatable(three)))"); luaL_dostring (L, str);
sprintf(str, "print(\"5 Metatable of four: \"..tostring(getmetatable(four)))"); luaL_dostring (L, str);
sprintf(str, "print(\"5 Metatable of five: \"..tostring(getmetatable(five)))"); luaL_dostring (L, str);
printf("\n");




return 0;
}


Share this post


Link to post
Share on other sites
Advertisement
Every light userdata shares the same metatable, if you want to assign different metatables you either need to use tables or full user data.

edit added Lua manual quote
http://www.lua.org/manual/5.1/manual.html#2.8
Quote:
Tables and full userdata have individual metatables (although multiple tables and userdata can share their metatables). Values of all other types share one single metatable per type; that is, there is one single metatable for all numbers, one for all strings, etc.

Share this post


Link to post
Share on other sites
Sign in to follow this  

  • Advertisement
×

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

GameDev.net is your game development community. Create an account for your GameDev Portfolio and participate in the largest developer community in the games industry.

Sign me up!