c++ - 嵌入式 Lua 和重载的 C++ 运算符

Question

我在我的 C++ 应用程序中嵌入了 Lua。

我有一个 Foo 类，我将它暴露给 Lua(通过 tolua++)。

Foo 重载了一些运算符，如下所示:

class Foo
{
   public:
      explicit Foo(const int i);
      bool operator==(const Foo& foo) const;
      bool operator< (const Foo& foo) const;
      int operator-(const Foo& foo) const;

   private:
      int m_ival;
};

我的问题是，在我的 Lua 脚本中，我可以在我的 Lua 脚本中使用如下所示的表达式吗:

f1 = Foo:new(42)
f2 = Foo:new(123)

if f1 < f2 then
   print(f2 -f1)
end

Answer 1

根据文档，tolua++ 支持这个 - 参见 Binding classes and methods - Overloaded operators :

tolua automatically binds the following binary operators:

operator+   operator-   operator*   operator/ 
operator<   operator>=  operator==  operator[]

For the relational operators, toLua also automatically converts a returned 0 value into nil, so false in C becomes false in Lua.

As an example, suppose that in the code above, instead of having:

Point add (Point& other); // add points, returning another one

we had:

Point operator+ (Point& other); // add points, returning another one

In that case, in Lua, we could simply write:

p3 = p1 + p2