如何在Lua 5.3中注册一个C ++类和函数 [英] How can I register a C++ class and function in Lua 5.3

问题描述

所以我一直使用这个游戏引擎一段时间，我可以创建一个使用内置事件的游戏，或者我可以使用C ++，但我最近试图嵌入Lua 5.3，但我有一个问题，如何注册一个特定的C ++类Lua，例如：
在游戏引擎的C ++中，我会改变背景颜色，如下：

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)
}

但我的问题是，我该怎么做在Lua？如何在Lua 5.3中注册该函数和类？

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

推荐答案

在 this example。

您创建/请求 metatable 与类名称，推成员函数（除了构造函数）到他和注册一个构造函数，它返回你的类作为userdata，链接metatable。

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.

需要在自表上设置字段__index，以便以后的成员访问引导metatable，而不是userdata。 __gc发生在垃圾收集 - 你的析构函数。因为Lua是用C编写的，所以分配userdata内存不会调用构造函数，所以类实例放在堆上，地址传递给Lua。

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.

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