Question

How can I pass a class member function to a non-class member function’s parameter? I am getting the following compile error:

error: argument of type ‘void (MyNamespace::MyClass::)(int*)’ does not match ‘void (*)(int*)’

Library.h

typedef void (*testCallback)(int* iParam);
void UsingTheFoo(testCallback Callback);

Library.cpp

void UsingTheFoo(testCallback Callback)
{
  int *p_int = new int;
  *p_int = 5;
  Callback(p_int);
}

MyClass.cpp

namespace MyNamespace
{

    void MyClass::fooCB(int* a)
    {
        printf("hey! %d\n", *a);
    }


    void MyClass::testo()
    {
        UsingTheFoo(fooCB);
    }

} // MyNamespace

I can not change the code in “Library”, I need to use “UsingTheFoo” in MyClass member functions. I am aware my way is wrong, I searched and found similar questions but couldn’t understand (braindead at the end of shift 🙂 ) any of them completely to adapt for my problem.

I’ve already read: http://www.parashift.com/c++-faq-lite/pointers-to-members.html :S

Answer 1

Make method that you wanna to pass as a callback as static. You’ve got this error because all methods have implicitly first parameter – pointer to an object, this, so their prototype doesn’t correspond to callbacks’.