class P { 
   P  
  public:
  P() { _self = 0; }
  virtual P* self() {
  	return _self?_self->self():this;
  	}
  virtual void attach(C* p) {
  	_self = p;
  	}
  private:
  P* _self;
  };
  
  class C : public P { 
   $$ C <= P  
  public:
  C() : P(this) { }
  C* self() { 
 ANSI/ISO
  	return _self?_self->self():this;
  	}
  void attach(P* p) {  
 rejected
  	p->attach(self()); 
  	} 
  void redirect(C* c) { _self = c; }
  private:
  C* _self;
  };