Dear Richard,

> Bill Spight <bspight at pacbell.net> wrote:
>         And, upon reflection, I think I understand your point about
>         PluggableSets better. Thank you. :-) But PluggableSets do not seem more
>         general than Sets.
>         
> PluggableSets can simulate Sets.
> Sets cannot simulate PluggableSets.
> 
> Doesn't that mean that PluggableSets are more general than Sets?
> 

Interesting idea. :-)

If ClassA inherits ClassB's behavior, but adds other behavior, ClassB is
a subclass of ClassA, but can simulate ClassA simply by not using the
added behavior, whereas ClassA cannot simulate ClassB without it. Hmmm.

Many thanks,

Bill