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From: Dmitry A. Kazakov <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada,misc.misc
Subject: Re: Out parameters in a function
Date: Wed, 17 Apr 2002 09:57:26 +0200
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Date: 2002-04-17T09:57:26+02:00
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On Tue, 16 Apr 2002 20:00:42 +0000 (UTC), "Kent Paul Dolan"
<xanthian@well.com> wrote:

>"John McCabe" <john.mccabe@emrad.ns.com> wrote:
>
> > type of thing, but I can't remember off-hand how you would use a
> > returned status with multiple return values!
>
>Well, if I'm not inventing capabilities, in C the syntax is fairly
>direct (and forgive that with several dozen languages mixed in my head I
>cannot write any one correctly without manual in lap, which I don't have
>these days):
>
>if
>(
>  (
>    aSomestructTypedVariable =
>      aSomestructReturningFunction
>      (
>        lots,
>        of,
>        parms
>      )
>  ).booleanPart
>)
>{
>  usefulVal = aSomestructTypedVariable.usefulPart;
>}

Same in Ada:

declare
   aSomestructTypedVariable : constant SomestructType :=
      aSomestructReturningFunction (...);
begin
   if aSomestructTypedVariable.booleanPart then
      usefulVal := aSomestructTypedVariable.usefulPart;
   end if;
end;

Not a big deal.

A real advantage [and possible the single one] of returned tuples of
values is when you are able to use them as a part of the parameter
list for some other subroutine. There are things that cannot be done
with temp variables + out parameters. For instance

Text :String := Get_Nobody_Knows_How_Many_Characters (...);

cannot be replaced with:

   Text : String; -- Error!
begin
   Get_Nobody_Knows_How_Many_Characters (..., Text);

---
Regards,
Dmitry Kazakov
www.dmitry-kazakov.de