Re: What's class?

["Jean-Pierre Rosen" <rosen.adalog@wanadoo.fr>]

bill a �crit dans le message <7avvpf$pfl@drn.newsguy.com>...
>Since any type that extends a parent type, also inherits its
operations,
>then in this case, writing
>
>         function is_full( stack: in bounded_stack'class)
>and
>         function is_full( stack: in bounded_stack)
>
>
>make no difference!
>
>correct?
There is a huge difference between a class-wide operation and an
inherited operation.
An inheritede operation conceptually is part of the definition of the
type, and can be redefined by any descendant. In a sense, the original
operation serves as a "default value" for descendants that don't care
to redefine it.
OTOH,  a class wide operation operates conceptually on the full class;
it is not part of the type definition, it is not inherited, and in
cannot be redefined.

The nice thing with inherited operations is that you can redefine them
if you whish; the nice things with class-wide opertions is that you
are certain that nobody redefined the operation behind your back to
make it do something else.

Given your constraints, choose the appropriate one...
---------------------------------------------------------
           J-P. Rosen (Rosen.Adalog@wanadoo.fr)
Visit Adalog's web site at http://perso.wanadoo.fr/adalog