c++ - 尝试调用成员函数指针将不起作用

Question

我知道成员函数指针有点棘手，如果函数指针不是类本身的成员，我可以调用它，但如果它是类的成员，我似乎无法调用它:

struct Window
{
    virtual void handleEvent() {};
    void (Window::*pHandleEvent)();
};

int main()
{
    Window w;
    void (Window::*fnptr)() = &Window::handleEvent;
    (w.*fnptr)(); // Works fine calling a local func ptr
    w.pHandleEvent(); // Calling its own member pointer doesn't work
    // Err: Expression preceding parentheses of apparent call must have
    // (pointer-to) function type
    (w.*pHandleEvent)();    // Doesn't work
    //Err: identifier "pHandleEvent" is undefined
    (w.*Window::pHandleEvent)();    // Doesn't work.
    // Err: A non-static member reference must be relative to a specific object.
}

Answer 1

您需要指定两个 Window 对象:一个要使用其指针，另一个要在其上调用方法。如果它们相同，则为

(w.*w.pHandleEvent)();

请注意优先级:如果您有 A Window::*ptm; 并且想要 A 对象的成员，则它是 (w.*ptm ).a_member.