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From: Dmitry A. Kazakov <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Out parameters in a function
Date: Tue, 16 Apr 2002 12:05:01 +0200
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Date: 2002-04-16T12:05:01+02:00
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On Tue, 16 Apr 2002 08:49:44 GMT, john.mccabe@emrad.ns.com (John
McCabe) wrote:

>On 15 Apr 2002 08:09:24 -0700, dennison@telepath.com (Ted Dennison)
>wrote:
>
>>"Nazgul" <darkelf@aim.homelinux.com> wrote in message news:<a9chqr$23e76$1@ID-107015.news.dfncis.de>...
>>> function ReadChar(f: File; c: out character) return boolean;
>>> 
>>> The function must return a boolean, so the only way to read the character is
>>> via the 'c' parameter. In other context, I use
>>...
>>> Is there any way of using c as an output parameter?
>>
>>No. In Ada functions take multiple "in" parameters, and return only
>>one value via the "return" machanisim. If you have multiple values you
>>need to return, you should be using a procedure, not a function.
>
>Unfortunate that they didn't follow the Occam example of having a
>function capable of returning multiple values!

Let they do. I.e. let a function return an object of anonymous record
type which components are returned values:

function Match_Pattern (..) return
   record
      Place : Position;
      Matched : String;
   end record;

How could we use such object? It does not well fit in a language with
named parameter association and very limited possibilities of matching
types by structure. IMO out parameters make more sense.

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