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From: Niklas Holsti <niklas.holsti@tidorum.invalid>
Newsgroups: comp.lang.ada
Subject: Re: If a routine should return two results, how should it be done?
Date: Sat, 26 Jul 2014 21:53:50 +0300
Organization: Tidorum Ltd
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Xref: number.nntp.dca.giganews.com comp.lang.ada:187909
Date: 2014-07-26T21:53:50+03:00
List-Id: <comp.lang.ada>

On 14-07-26 21:00 , Victor Porton wrote:
> If a routine should return two results, how should it be done?

Pick any method you like (but not case 2, if you want to be compatible
with pre-2012 Ada).

> 1. procedure with two out arguments;
> 
> 2. function with one out argument;
> 
> 3. create specific record type for the result type of the function?
> 
> What are advantages and disadvantages of each variant?

The same as in any other language which offers these choices, which is
most languages (well, for C you must use pointers for "out" and "in
out", but logically it is the same thing).

Oh, compared to C++ there is a small difference, in that Ada allows
overloading on the result type; in C++ one would perhaps avoid choices 3
(and 2) for that reason.

Personally I would first consider if the "two results" are logically
connected in such a way that they actually represent one composite
result, and then I would have a subprogram with one result -- no
problem. Otherwise, I would use choice 1. Choice 2 would be acceptable
to me only in very special cases, such as a random-number generator.

-- 
Niklas Holsti
Tidorum Ltd
niklas holsti tidorum fi
      .      @       .