Question

I want to define a member function in class and use its pointer. I know that I can use static member function but the problem with it is that I can only access the static members of the class. Is there a way other than static member function to be able to get function pointer.

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To be more specific: There is a library which I’m using which gets a function pointer as its input. I want to write a member function and assign its function pointer to that external library. Should I create an object of class or use this pointer to do this?

Answer 1

You can get the pointer of the method, but it has to be called with an object

typedef void (T::*MethodPtr) ();
MethodPtr method = &T::MethodA;
T *obj = new T();
obj->*method();

If you need to have non-object pointer and you want to use object then you have to store instance of object somewhere, but you are restricted to use only one object (singleton).

class T {
  static T *instance;
public:
  T::T() {
    instance = this;
  }
  static void func() {
    instance->doStuff();
  }
  void doStuff() {}
};

If library supports user data for function pointers, then you may have multiple instances

class T {
public:
  static void func(void *instance) {
    ((T*)instance)->doStuff();
  }
  void doStuff() {}
};