Example 1: (a) Sending messages in Objective C; (b) specifying 
the selector at run-time.

(a)

[myButton setName: "Ok"];
[myButton setSizeDx: 100 dy: 20];
[[myDialog getButton: "Ok"] disable];

(b)

SEL action = @selector (setName:);
[myButton perform: action with: "Ok"];
//  ...which is the same as:
__msg (myButton, action, "Ok");




Example 2: 

class Base {
public
    virtual void Foo ();
};
void Base::Foo () { printf ("Base::Foo\n"); }
class Other : Base {
public
    virtual void Foo ();
};
void Other::Foo () { printf ("Other::Foo\n"); }
void test (Base* object) { object->Foo (); }
void main ()
{
    Base  base;
    Other other;
    test (&base);    // prints "Base::Foo"
    test (&other);   // prints "Other::Foo" 
}

Example 3: 

(a)

typedef void (Base* object)
void test (Base* object)
{
    PtrMember ptr = Base::Foo;
    (object->*ptr) (); // calls object->Foo ()
}


(b)

class A { /* ... */ };
class B { /* ... */ };

typedef void (A::*PtrAMember)();
typedef void (B::*PtrBMember)();

void test (A* a, B* b, PtrAMember pa)
{
    PtrBMember pb = (PtrBMember)(pa); // cast error
    (a->*pa) ();
    (b->*pa) ();                      // error. bad base class

    (b->*pb) ();
}