How can I register a C++ class and function in Lua 5.3

Question

So I've been using this game engine for quite some time, I can create a game using that with either the built-in events or I can use C++ but I've recently tried to embed Lua 5.3 to it, but I'm having problems on how to register a certain C++ class to Lua, example: In the game engine's C++, I would change the background color like this:

#include "GDCpp/RuntimeScene.h"

void changeBackground(RuntimeScene & scene)
{
     scene.SetBackgroundColor(250,100,85)
}

But my problem is, how can I do that in Lua ? how can I register that function and class in Lua 5.3?

Youka Youka · Accepted Answer · 2015-07-13T13:44:08

Hava a look on this example.

You create/request a metatable with the class name, push member functions (except constructor) into him and register a constructor function which returns your class as userdata, linked with the metatable.

Setting field "__index" on self table is required that later member access leads to the metatable, not userdata. "__gc" happens on garbage collection - your destructor. Because Lua is written in C, allocating userdata memory doesn't invoke constructors, so the class instance was put on the heap and the address passed to Lua.

How can I register a C++ class and function in Lua 5.3

1 Answers