std :: function - >函数指针 [英] std::function -> function pointer

问题描述

这里是一个代码：

#include <functional>
using namespace std::tr1;

typedef void(*fp)(void);

void foo(void)
{

}

void f(fp)
{

}

int main()
{
  function<void(void)> fun = foo;
  f(fun); // error
  f(foo); // ok
}

最初我需要从非静态类方法，因为我需要在函数调用之间保存数据。我尝试了 std :: tr1 :: bind 和 boost :: bind ，但他们返回函数对象，其中，我可以看到，不能铸到纯函数指针。虽然函数签名（ SetupIterateCabinet ）需要一个纯func指针。

Originally i need to make a function pointer from non-static class method because i need to save data between function callings. I tried std::tr1::bind and boost::bind, but they return functional object, not pointer, which, as i can see, can't be "casted" to pure functional pointer. While the function signature (SetupIterateCabinet) demands a pure func pointer exactly.

我需要一个建议如何解决问题。谢谢

I need an advise how to solve the problem. Thank you.

推荐答案

您已经大大简单化了您的实际问题，把你的问题到的 XY问题。让我们回到您的真实问题：如何调用 SetupIterateCabinet 作为回调。

You've greatly oversimplified your real problem and turned your question into an XY problem. Let's get back to your real question: how to call SetupIterateCabinet with a non-static member function as a callback.

某些类：

class MyClass
{
public:
    UINT MyCallback(UINT Notification, UINT_PTR Param1, UINT_PTR Param2)
    {
        /* impl */
    }
};

为了使用 MyClass :: MyCallback 作为 SetupIterateCabinet 的第三个参数，您需要为上下文 c传递 MyClass * / code>参数，并使用一个简单的shim函数取得 Context 参数，并做正确的事情：

In order to use MyClass::MyCallback as the third argument to SetupIterateCabinet, you need to pass a MyClass* for the Context argument and use a plain shim function to take that Context argument and do the right thing with it:

UINT MyClassCallback(PVOID Context, UINT Notification, UINT_PTR Param1, UINT_PTR Param2)
{
    return static_cast<MyClass*>(Context)->MyCallback(Notification, Param1, Param2);
}

int main()
{
    MyClass mc;
    SetupIterateCabinet(_T("some path"), 0, MyClassCallback, &mc);
}

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