Re: disjoint ranges ?

[Lao Xiao Hai <laoxhai@ix.netcom.com>]

Robert A Duff wrote:

> Robert Dewar <robert_dewar@my-deja.com> writes:
>
> > No, it could be over all damaging. Every new feature you add
> > to a language damages it by adding to the understanding,
> > programming, description, and implementation complexity.
>
> Quite true, but you don't necessarily have to add features in order to
> add functionality.  Sometimes, making a feature more powerful can add
> functionality without increasing complexity.

So, making a feature more powerful might be something such as being
able to overload the "in" membership test.   For some reason, this
operator is not really a first class operator in Ada.   I have often
wondered about the rationale for that decision.    If it were overloadable,

one could simply declare a membership function that would enable
disjoint membership tests.

I do see some problems with this when considered in terms of the
for loop since it would be a strange loop, indeed, that had disjoint
values.  On the other hand, that could also be an alternate solution
to the absence of a step capability.   Also, it does not have to
be incompatible with the requirement that the value be discrete.

Any thoughts on this?

Richard Riehle