Does it make sense to remove slots ?

[Tim Moore]

On Nov 7, 2004, at 4:25 PM, Peter van Rooijen wrote:

> Tim Moore wrote:
>
>> That's a pretty well-accepted object oriented design philosophy known 
>> as Liskov's Substitution Principle. It's actually often phrased in 
>> terms of "the circle/elipse problem" as a matter of fact.
>
> Hi!
>
> While I agree that shape-mutable circles may make little sense being 
> implemented as subclasses of ellipse, I would add that LSP is a vision 
> on subtyping, not on inheritance/subclassing.
>
> Inheritance/subclassing is just what it is. The language that is your 
> context defines how inheritance works and what it means. There is no 
> reason to limit its use to the implementation of subtypes.
>
>

That is a good point, but in this case the question boils down to: why 
do you want to make Circle derive from Ellipse at all? Is it to inherit 
behavior? I think for most people, it is just because they know that 
geometrically a circle is a kind of ellipse, so they feel it should be 
a subtype.
-- 
Tim Moore