C ++函数作为函数指针 [英] C++ functor as a function pointer

问题描述

我有一个Functor，我需要发送到一个函数接收一个函数指针作为参数（如 CreateThread ）。

I have a Functor which I need to send to a function which receives a function pointer as a parameter (such as CreateThread).

我可以将它转换为静态方法地址吗？如果没有，我该怎么办呢？

Can I convert it to a static method address somehow? And if not, how can I do it?

推荐答案

不，不能将类类型的对象转换为函数指针。

No, you can't convert a class-type object to a function pointer.

但是，您可以编写一个非成员包装器函数来调用正确实例上的成员函数。许多API，包括 CreateThread ，允许你提供一个指针，当它调用你的回调（ CreateThread ，这是 lpParameter 参数）。例如：

However, you can write a non-member wrapper function that calls the member function on the right instance. Many APIs, including CreateThread, allow you to provide a pointer that it will give back to you when it calls your callback (for CreateThread, this is the lpParameter parameter). For example:

DWORD WINAPI FunctorWrapper(LPVOID p)
{
    // Call operator() on the functor pointed to by p:
    return (*static_cast<FunctorType*>(p))();
}

// Used as:
FunctorType f;
CreateThread(0, 0, &FunctorWrapper, &f, 0, 0);

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