Re: Ada.Strings.Bounded

[Adam Beneschan <adam@irvine.com>]

On Apr 22, 11:47 am, Eric Hughes <eric....@gmail.com> wrote:

> So now wait.  When I declare
>     type X is range 0 .. 99 ;
> does that mean that the value 100 is a value of type X?

Yes.  See 3.2.1(6).  This declaration defines both a *type* X and its
*first subtype* X.  The type X includes all integers.  The subtype X
imposes a constraint of 0..99 on that type.  When you declare

    Var : X;

and then assign something into Var, the expression's value will be
checked against the subrange 0..99, just as if you had said

    type Y is range 0..1_000_000_000;
    subtype YY is Y range 0..99;

    Var : YY;

> And so now I have developed a Strong Opinion.  This is a travesty.  A
> probably-irredeemable travesty. This is so completely counter-
> intuitive that I have a hard time believing that competent people came
> up with this way of writing the definition.  It's unnecessary.  There
> are far better ways of defining this, and they don't break any
> existing syntax.

Back on April 15, in a different thread, you said "Make the formal
standard normative, the human language expository", arguing that it
would be OK for the formal standard to be inaccessible to human
programmers.  Now, in a case where the formal standard has been made a
little bit complex in order to get the language to work they way they
wanted it to work, then you complain about it not being intuitive.  I
don't think you can have it both ways.

But I am going to complain bitterly about one thing: you are way out
of line to insinuate that the people who came up with the standard are
incompetent.  WAY out of line.  I know how much work the people who
work on the standard put into it, and how much thought they put into
making sure everything fits together and all the bases are covered
while at the same time trying to make it reasonably readable.  So even
if you don't understand why the standard's authors defined something
the way they did, you can assume there's a 99.9999% chance that there
was a darn good reason why they did it that way.  In this particular
case, I think they saw a need to support static expressions with
intermediate results that were larger than a machine integer, and the
type/subtype definitions they came up with allowed them to accomplish
this.

                                 -- Adam