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169

answers:

1

I'm trying to wrap a class from a library I'm using in Lua. Specifially, I'm trying to wrap the color class from SFML. The full source for the color class can be seen here and here.

This is the function that's that I'm failing in.

int SFColor_new(lua_State* L)
{
    // omitting part where I set r, g, b, and a
    new (lua_newuserdata(L, sizeof(Color))) Color(r, g, b, a); // Line 47
    luaL_getmetatable(L, LuaInfo<Color>::myMetaTableName);
    lua_setmetatable(L, -2);
    return 1;
}

And this is the error

LuaSFMLColor.cpp: In function ‘int ag::SFColor_new(lua_State*)’:
LuaSFMLColor.cpp:47: error: no matching function for call to ‘operator new(unsigned int, void*)’
<built-in>:0: note: candidates are: void* operator new(unsigned int)
make: *** [game] Error 1

I do similar things in a few other places without running into this error, so I'm not sure what would be causing it. Looking at the Color's source code I don't see anything weird or out of the ordinary, and I've run out of ideas. I've also tried using the default constructor (i.e. no arguments) and then just setting the value afterward, but that didn't do any good either.

+11  A: 

To use the standard placement form of new you have to #include <new>.

The form of new that you are using requires a declaration of void* operator new(std::size_t, void*) throw();.

You don't have to #include <new> to use non-placement new.

Charles Bailey
+1! That didn't occur to me at all. I have to delete my answer.
+1. I never knew that. Perhaps a lot of STL headers use placement new (for rather obvious reasons) and I never had to #include it manually myself, but if you had a file where you didn't have, say, vector, then you might need to manually include it.
DeadMG
This did it. I never realized it either until this was posted. It must be buried in some of the other headers I've been using without me ever knowing. Thanks. :) You learn something new everyday. (pun intended)
Alex
@Alex: +1 for pun =)
Cogwheel - Matthew Orlando