Why Can Penguins Be Subtyped as Birds But Motorcycles Not as Cars in OOP?

[tmt1]

For object oriented programming, why is is acceptable to have a
penguin be a subtype of bird even though a penguin has different
attributes than a bird(supposing we have a fly method) and yet it is
unacceptable for for Motorcycle to be a subtype of Car even though it
has the same behaviour (ie drive method)?

 

[I like Serena]

For object oriented programming, why is is acceptable to have a
penguin be a subtype of bird even though a penguin has different
attributes than a bird(supposing we have a fly method) and yet it is
unacceptable for for Motorcycle to be a subtype of Car even though it
has the same behaviour (ie drive method)?

Hi tmt!

Both Car and Motorcycle are specializations of a MotorizedVehicle.
That's the one that has for instance a drive method.
Put otherwise, we can't say that a Motorcycle "is a" Car, since that is just not true.

On the other hand, we can treat a penguin as a more specialized version of a bird.