c ++函数成员指针 [英] c++ Function member pointer

问题描述

我已经阅读了几个帖子，但是似乎找不到我正在寻找的示例代码，如果任何人可以给我一些帮助，我会非常感激它。

I have read several posts about this, but can't seem to find exactly what i am looking for with example code if anyone could give me some help i would highly appreciate it.

在我的标题中有：

void addEvent(void (*func)(Pack  *));

void triggerEvents(Pack * );

std::list<void(*)(Pack *)> eventList;

和cpp文件

void DNetwork::addEvent(void (*func)(Pack *)){
    eventList.push_back(func);
}

void DNetwork::triggerEvents(Pack * pack){
    for (std::list<void (*)( Pack *)>::iterator it = eventList.begin(); it !=         eventList.end() ;it++ ){
        (*it)(pack);
    } 
}

这对自由功能很好，添加成员函数到此列表我得到一个错误。

This works fine with free functions, but when i try to add a member function to this list i get an error. Does anyone know how to store a member function (from random class objects) inside a pointer?

推荐答案

对于成员函数，你需要一个成员函数绑定。成员函数是具有其类的隐式参数的正常函数。所以你需要一个binder。如果你使用c ++ 11，你可以使用std :: bind和std :: function，也可以对非c ++ 11代码使用boost :: bind和boost :: function。

For member function you need a bind. A member function is a "normal function" that has an implicit parameter of its class. So you need a binder. If you use c++11 you can use std::bind and std::function or you can use boost::bind and boost::function for non c++11 code.

typedef std::function< void ( Pack* ) > MyFunction;
void addEvent( MyFunction f );
void triggerEvents( Pack* );
std::list< MyFunction > eventList;

void DNetwork::addEvent( MyFunction f )
{
    eventList.push_back( f );
}

void DNetwork::triggerEvents( Pack *pack )
{
    for ( auto it = eventList.begin(); it != eventList.end(); it++ )
    {
        (*it)(pack);
    } 
}

现在如果我有类A， code> doA（Pack *）我会写：

Now if I have the class A with the method doA( Pack* ) I will write:

A a;
Pack pack;
DNetwork d;
d.addEvent( std::bind( &A::doA, &a, &pack ) );

或者更好的方法是使用Boost.Signal或者使用发布者/子模式

Or even better you can use Boost.Signal or you can use the Publisher/Subcriber Pattern

编辑
As @DavidRodríguez-dribeas建议：bind不应该使用& pack参数，因为成员函数的参数在triggerEvents中的调用位置提供。正确的方法是：

Edit As @DavidRodríguez-dribeas suggest: The bind should not take the &pack argument, as the argument to the member function is provided at the place of call in triggerEvents. The correct way is:

A a;
Pack pack;
DNetwork d;
d.addEvent( std::bind( &A::doA, &a, std::placeholders::_1 ) );
d.triggerEvents( &pack );

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