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From: Aggro on 20 Nov 2007 17:56
I have a program, which prints out this:
--------- output -----------
Button 1:a
Button 2:a
--------- output -----------

This is exactly what I want and the program works correctly. The problem
is that I can only make the callback functions to work in my derived
class (MyWnd) by declaring virtual functions to my base class ( Window
). This is not a very good solutions, since I could end up having
several different callback functions which I would rather not have in
the Window class. And I would also like to be able to pick any member
function name i want to, in the derived classes.

So the question is. Can I keep the functionality I now have, without the
virtual functions in my base class? I also need to be able to derive
other classes from Window and implement similar behaviour to those too.
And if I can, how do I do that?

-------------- main.cpp -----------------
#include <iostream>

class Window;

class Button
{
typedef void (Window::*funcName)( char x );

public:
void Connect( Window &wnd, funcName func )
{
mwnd = &wnd;
mfunc = func;
}

void Push()
{
(mwnd->*mfunc)('a');
}

Window *mwnd;
funcName mfunc;
};

class Window
{
public:
virtual void Button1( char x )
{

}

virtual void Button2( char x )
{

}
};

class MyWnd : public Window
{
public:
void Button1( char x )
{
std::cout << "Button 1:" << x << std::endl;
}

void Button2( char x )
{
std::cout << "Button 2:" << x << std::endl;
}

void Create( Button *b, Button *b2 )
{
b->Connect( *this, &Window::Button1 );
b2->Connect( *this, &Window::Button2 );
}
};

int main()
{
Button *b = new Button();
Button *b2 = new Button();
MyWnd wnd;
wnd.Create( b, b2 );
b->Push();
b2->Push();
delete b;
delete b2;

return 0;
}

-------------- main.cpp -----------------
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