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Date: Wed, 23 Apr 2008 12:42:32 +0200
From: Georg Bauhaus <rm.dash-bauhaus@futureapps.de>
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Subject: Re: Ada.Strings.Bounded
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Date: 2008-04-23T12:42:33+02:00
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Robert A Duff schrieb:

>> And so now I have developed a Strong Opinion.  This is a travesty.
> 
> I agree it's confusing.  But "travesty" is too strong.  In practise,
> none of this matters much.
> 
> Don't you want to be able to say "(Blah + 1) mod 99" without overflow
> (where Blah is of subtype X)?

Hmm, less explicit and more lazy programming is
attractive to many programmers, so just write expressions
of a type that cannot be named, just in case of integers.
But how about this:

procedure Ex is
    type E is (A, B, C);
    X: E;
begin
    X := E'pred(E'succ(C));
end Ex;

In this case there is a static constraint error. Is this
consistent with anything but the Ada LRM's exception for
"integer convenience"?

Without of course knowing why the choices were made the
way they were made for the LRM, my conclusion is that
many programmers still prefer high school ideas about
numbers over the theory of computer numbers.

Is it really inacceptable to write

   Larger_Type'(Blah + 1) mod 99;

The expression doesn't hide a secret about its
value range.