Re: Ideas for Ada 200X

[Robert A Duff <bobduff@shell01.TheWorld.com>]

"Warren W. Gay VE3WWG" <ve3wwg@cogeco.ca> writes:

> I disagree that it is "urgent". What is your case for urgency here?
>  From what I have seen, most people that promote the idea, are just
> "typing challenged" (yes I know ++i is different than i++).

Well, I like the idea of an increment operation, and my reasoning has
nothing to do with typing.  The problem is code duplication: you have to
write "I" twice in "I := I + 1;".  No big deal if it's just "I", but it
could be a complicated name, so the reader has to careful compare the
text, and also worry about whether the name has side effects.

> Consider this: the Ada95 language is already large and complex. Is
> there really enough justification for complicating it with ++i/i++
> issues?  Not to meantion that --i may appear like a comment?!?!? ;-)

Of course, if Ada had such a thing, it shouldn't be called "--".
If I were the boss, it would be called Incr and Decr.  They would be
procedures, not functions, because I don't like to encourage that sort
of side effect in the middle of expressions.  So in that regard, it
would be different from C's ++ and --.  There's no pre-increment
vs. post-increment issue.

Note that an earlier version of Ada 9X allowed untagged class-wide
types.  That feature, plus giving a true name to root_integer, would
have allowed such things to be written *in the language*:

    procedure Incr(X: in out Root_Integer'Class; By: Root_Integer'Class);

    Incr(A[I].X);
    Incr(A[I].X, By => 2);

Of course, you can define such a procedure in Ada 95, but you have to do
it for every integer type, and it's just not worth the trouble.  If you
could do it once, for all integer types, it would be worth it.

- Bob