如何将一个方法作为回调传递给另一个类？

本文介绍了如何将一个方法作为回调传递给另一个类？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！ 问题描述

我有一个关于使用tr1 :: function回调的问题。我定义了以下内容：

I have a question regarding callbacks using tr1::function. I've defined the following:

class SomeClass { public: typedef std::tr1::function<void(unsigned char*, int)> Callback; void registerCallback(Callback); private: Callback callback; }

我定义了另一个类：

class SomeOtherClass { void myCallback(unsigned char*, int); }

现在我想注册我的函数'myCallback'在类'SomeClass'使用方法'registerCallback'。但是，它不工作。我已经看了关于功能的boost文档，似乎合法使用（成员）类的方法的回调。我错了吗？

Now I want to register my function 'myCallback' as callback at class 'SomeClass'using the method 'registerCallback'. However, it is not working. I've had a look on the boost documentation on the function and it seems legit to use (member) methods of a class for callbacks. Am I wrong?

提前感谢！

推荐答案

参数，一个这个指针，以便知道调用该函数的对象。通常，它是隐藏的，但是要绑定一个成员函数到std :: function，你需要显式地提供类型的模板参数。

Member functions have an implicit first parameter, a this pointer so as to know which object to call the function on. Normally, it's hidden from you, but to bind a member function to std::function, you need to explicitly provide the class type in template parameter.

#include <functional> #include <iostream> struct Callback_t { void myCallback(int) { std::cout << "You called me?"; } }; class SomeClass { public: SomeClass() : callback() { } typedef std::function<void(Callback_t*, int)> Callback; // ^^^^^^^^^^^ void registerCallback(const Callback& c) { callback = c; } void callOn(Callback_t* p) { callback(p, 42); } private: Callback callback; }; int main() { SomeClass sc; sc.registerCallback(&Callback_t::myCallback); Callback_t cb; // we need an instance of Callback_t to call a member on sc.callOn(&cb); }

输出： $ c>;

Output: You called me?;