类方法的回调（C ++） [英] Callbacks from a class method (C++)

问题描述

我有一个Button类。
当我点击这个按钮，它的selected（）方法被调用。

I have a Button class. When I click this button, it's selected() method is called.

//Button.cpp
void Button::selected(){
//Do Something
}

//Player.cpp
void Player::Jump(){
//Jump!
}

我也有一个Player类。
我想要这样，当我点击按钮，播放器方法的Jump（）
被调用。我想我可以只链接Player类与按钮。
但是我意识到按钮类将有很多其他用途，而不是
只是让我的玩家跳。 （即：一个菜单选择器？让玩家移动？等等）

I also have a Player class. I wanted to make it so that when I click the button, the player method's Jump() is called. I suppose I could just link the Player class with the button. But then I realized that the button class is going to have many other uses, and not just letting my player jump. (ie: a menu selector? make the player move? etc.)

所以我想包括一些回调，但我不太熟悉

So I was thinking of including some kind of a callback, but I'm not too familiar with them and I'm having trouble understanding some tutorials I've read.

有人可能告诉我如何使用selected（）方法来接受任何函数/方法作为参数并在方法体中执行？

Could someone show me how I would use the selected() method to take in any function/method as a parameter and execute it in the method body?

推荐答案

这里是一个函数方法， / p>

Here's a functor approach where you pass a function as an argument:

template <typename functor_t>
void Button::selected(functor_t func){
  // ...
  func();
  // ...
}

参数可以是函数指针，或一个函数对象：

The argument can be a function pointer, or a function object:

 struct functor {
   void operator()() {
     // stuff
   }
 };

 void function() {
   // stuff
 }

$ b b

使用指向成员的指针调用 void method（）：

struct foo {
  void bar() {
    std::cout << "hello";
  }
};

template <typename class_t>
void function(class_t& c, void (class_t::* mp)()) {
  (c.*mp)();
}

foo x;
function(x, &foo::bar);

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