如何将参数传递给std :: bind到函数？ [英] How to pass argument to std::bind to a function?

问题描述

我有以下使用std :: bind的代码：

I have the following code which used std::bind :

 EventListenerCustom* _createNewObjectlistener = 
eventDispatcher->addCustomEventListener(Constants::MY_EVENT, 
std::bind(&MyClass::MyFunction, this, std::placeholders::_1));

似乎我创建了许多不同类型的对象侦听器，其中唯一的区别是事件，而函数被调用。如果我想将上述代码封装到一个函数中：

It seems I create many different kinds of object listeners, where the only difference is the event, and the function being called. If I wanted to encapsulate the above code into a function:

• 如何将MyClass :: MyFunction作为函数的参数传递？ / li>
  
• 函数签名和参数是什么样的？

我想函数看起来像这样：

I imagine the function would look something like this:

EventListenerCustom* MyFunc(<What Goes Here> functionToBeBound,<What goes here> object,std::string EVENT){
    EventListenerCustom* eventListener = eventDispatcher->addCustomEventListener(EVENT, std::bind(functionToBeBound, object, std::placeholders::_1));
    return eventListener;
}

函数应该是什么样？我怎么称呼它？

What should the function look like ? And How do I call it? What would the calling code look like?

编辑：具体细节：

我有很多侦听器对象，它们是以相同的方式创建：

I have many listener objects which are created in identical ways:

auto eventDispatcher = _dragNode->getEventDispatcher();

_createNewObjectlistener = eventDispatcher->addCustomEventListener(Constants::MY_EVENT, std::bind(&MyClass::myOtherFunction, this, std::placeholders::_1));

_moveNewObjectlistener = eventDispatcher->addCustomEventListener(Constants::MY_EVENT2 std::bind(&MyClass::myFunction, this, std::placeholders::_1));

Constants :: MY_EVENT等只是const char *。

Constants::MY_EVENT etc are just const char* .

唯一的区别是调用了Function，并将字符串常量用作事件名称。如何将其封装到函数中？我在下面尝试了John Zwinck的解决方案，但是由于某种原因，由于编译器抱怨，我无法将其编译：

The only difference is the Function being called, and the string constant used as an event name. How can I encapsulate this into a function ? I have tried John Zwinck's solution below, but for some reason I can't get it to compile because the compiler complains:

: No viable conversion from '__bind<void (*&)(cocos2d::EventCustom *), MyNameSpace::MyClass *, const std::__1::placeholders::__ph<1> &>' to 'const std::function<void (EventCustom *)>'

推荐答案

为简化起见，请为指向 MyClass 中具有适当签名的任何成员函数的指针创建一个typedef：

To make it simpler, create a typedef for a pointer to any member function in MyClass which has the appropriate signature:

typedef void (MyClass::*MyMemberFn)(int); // replace int and void as needed

然后：

EventListenerCustom* MyFunc(MyMemberFn functionToBeBound, MyClass* object, std::string EVENT){
    return eventDispatcher->addCustomEventListener(EVENT, std::bind(functionToBeBound, object, std::placeholders::_1));
}

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