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From: "Corey Ashford" <yeroca7@rocketmail.com>
Subject: Re: new language construct proposed
Date: 1998/02/14
Message-ID: <6c5k86$r9k$1@usenet.rational.com>#1/1
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References: <6avo1d$sul@lotho.delphi.com> <dewar.886366536@merv>
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Organization: Rational Software
Newsgroups: comp.lang.ada
Date: 1998-02-14T00:00:00+00:00
List-Id: <comp.lang.ada>



Robert Dewar wrote in message ...
>tmoran said
>
><<How is that different from
>  if boolean_expression then raise exception_name;end if;
>>>
>
>Well of course, as we all understand, it is *not* different at all. We
>are talking minor convenience here, nothing more. But note that the
>above argument would equally well argue against the inclusion of
>
>   exit loopname when <<expression>>
>
>in the language.
>
>I think the reason that we justify it for exit, and not for raise
>(and most CERTAINLY not for all simple statements, nasty thought ...)
>is that exit is rather special since it is essentially part of the
>structure of a loop.
>

If you don't like the "if" statement, a procedure call would work too, but
it's not terribly pretty:

procedure Raise_When(Condition : Boolean; Exception_Id:
Ada.Exceptions.Exception_Id; Message : String := "") is
begin
    if Condition then
        Ada.Exceptions.Raise_Exception(Exception_Id, Message);
    end if;
end Raise_When;
pragma inline(Raise_When);

An example usage:

Raise_When(a > 17 and b = 0, Constraint_Error'identity, "Ephemeris Error");

This way you can add a string to the exception if desired.  Also, you could
null out
the body of this routine when you're getting ready to ship, to improve
performance.
Since it's inline, it doesn't cost you much.