From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00
	autolearn=unavailable autolearn_force=no version=3.4.4
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!feeder.eternal-september.org!nntp-feed.chiark.greenend.org.uk!ewrotcd!newsfeed.xs3.de!io.xs3.de!news.jacob-sparre.dk!franka.jacob-sparre.dk!pnx.dk!.POSTED.109.57.116.186.mobile.3.dk!not-for-mail
From: Jacob Sparre Andersen <jacob@jacob-sparre.dk>
Newsgroups: comp.lang.ada
Subject: Re: How to get Ada to =?windows-1252?Q?=93cross?= the
 =?windows-1252?Q?chasm=94=3F?=
Date: Sun, 06 May 2018 18:58:36 +0200
Organization: JSA Research & Innovation
Message-ID: <87o9hsu3er.fsf@jacob-sparre.dk>
References: <1c73f159-eae4-4ae7-a348-03964b007197@googlegroups.com>
	<878t9nemrl.fsf@nightsong.com>
	<d64089d4-af9d-43d9-b72b-a73d3fff1f00@googlegroups.com>
	<bf8f8498-f017-47dd-bf1f-188c7ceb5b28@googlegroups.com>
	<ed222259-b860-41a1-82ad-62f93d941faf@googlegroups.com>
	<fl3pbpF73fsU1@mid.individual.net>
	<r0bqedllrrbsihtoplg5qccap3ljc4rikl@4ax.com>
	<lya7tezfty.fsf@pushface.org> <87h8nl50rw.fsf@nightsong.com>
	<fl6i3lFprddU1@mid.individual.net> <87d0y97lda.fsf@nightsong.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=iso-8859-1
Content-Transfer-Encoding: 8bit
Injection-Info: franka.jacob-sparre.dk;
 posting-host="109.57.116.186.mobile.3.dk:109.57.116.186";
	logging-data="21912"; mail-complaints-to="news@jacob-sparre.dk"
User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.4 (gnu/linux)
Cancel-Lock: sha1:fFgMTYprqTYncJ6qy+1PgnqLi0c=
Xref: reader02.eternal-september.org comp.lang.ada:52043
Date: 2018-05-06T18:58:36+02:00
List-Id: <comp.lang.ada>

Paul Rubin wrote:
> Niklas Holsti <niklas.holsti@tidorum.invalid> writes:

>> One reason is that when a function evaluates an expression that
>> creates an object of a large, dynamic size (eg. an array expression)
>> on the secondary stack, this object can be returned /in situ/ as the
>> function's return value, without being copied.
>
> Ok, but that pattern is so common that allocating the space in the
> primary stack before calling the function is a standard optimization
> that every serious C++ compiler knows how to do.  Then the function
> writes the result into the primary stack and the caller can still use
> it after the function returns.  Could Ada not do it the same way?

How would you do it with this example?

   with Ada.Numerics.Discrete_Random;
   with Ada.Strings.Fixed;
   with Ada.Text_IO;
   
   procedure Random_String is
   
      subtype Lengths is Integer range 10 .. 20;
   
      package Random_Lengths is
        new Ada.Numerics.Discrete_Random (Result_Subtype => Lengths);
   
      Generator : Random_Lengths.Generator;
   
      function Example (C : in Character) return String is
         use Ada.Strings.Fixed;
      begin
         return Random_Lengths.Random (Generator) * C;
      end Example;
   
   begin
      Random_Lengths.Reset (Generator);
   
      Ada.Text_IO.Put_Line (Example ('H'));
      Ada.Text_IO.Put_Line (Example ('e'));
      Ada.Text_IO.Put_Line (Example ('l'));
      Ada.Text_IO.Put_Line (Example ('l'));
      Ada.Text_IO.Put_Line (Example ('o'));
   end Random_String;

Greetings,

Jacob
-- 
»But you have to be a bit wary of a ship that collects
 snowflakes.«                                  -- Diziet Sma