//The "All birds can fly, 
//penguins are birds, 
//penguins can't fly, 
//un oh" problem

class Bird
{
	public:
		void Fly();

	private:
		...
};

class Penguin: public Bird
{
	...
};


class Bird
{
	...
};

class FlyingBird: public Bird
{
	public:
		void Fly();
	...
};

class NonFlyingBird: public Bird
{
	...
};

class Penguin: public NonFlyingBird
{
	...
};


void error( const CString& Message); //Defined elsewhere

class Penguin: public Bird
{
	void fly() {error(Peguins can't fly!);}
};