终于找到了C++成员函数做函数指针的完美解决办法

当然,这是转自别人的:https://www.codenong.com/19808054/

之前因为这个没少废精力啊,这里记一下,感谢外国友人的回答.

#include <iostream>
#include <functional>
#include <string>
#include <sstream>
#include <memory>

using namespace std;

template <typename T>
struct Callback;

template <typename Ret, typename... Params>
struct Callback<Ret(Params...)>
{
    template <typename... Args>
    static Ret callback(Args... args) { return func(args...); }
    static function<Ret(Params...)> func;
};

// Initialize the static member.
template <typename Ret, typename... Params>
function<Ret(Params...)> Callback<Ret(Params...)>::func;

class Foo
{
public:
    void print(int* x) { // Some member function.
        cout << *x << endl;
    }
};

typedef  void (*cFunc)(int*);

int main()
{
    Foo foo; // Create instance of Foo.
    // Store member function and the instance using bind.
    Callback<void(int*)>::func = bind(&Foo::print, foo, placeholders::_1);

    // Convert callback-function to c-pointer.
    cFunc c_func = static_cast<decltype(c_func)>(Callback<void(int*)>::callback);

    // Use in any way you wish.
    unique_ptr<int> iptr{new int(5)};
    c_func(iptr.get());

    int data = 10;
    c_func(&data);
}