Pointer to member function

[AndreFratelli]

Hi guys =) need a little help here... Shouldn't this work?

class MyClass
{
public:
void method() {}
void (MyClass::*_callback)();
};

int main()
{
MyClass b;

b._callback = &MyClass::method;

(b.*_callback)(); // error C2065: '_callback' : undeclared identifier

return 0;
}

Fratelli

[Stephen Hewitt]

No, it shouldn’t work. Replace this:

(b.*_callback)();

with this:

(b.*(b._callback))();

C++ member function pointers are not like delegates in C#. The pointer MyClass::_callback identifies a member function of MyClass which returns void and takes no parameters (and has the calling convention __thiscall): it doesn’t specify which instance of MyClass. The fact that the pointer is a member of the class is incidental and is probably what’s confusing you.

Steve