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From: "Alex R. Mosteo" <devnull@mailinator.com>
Newsgroups: comp.lang.ada
Subject: Re: Amount of copying on returned constant objects
Date: Mon, 18 Jun 2007 20:14:15 +0300
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Date: 2007-06-18T20:14:15+03:00
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Dmitry A. Kazakov wrote:

> On Fri, 15 Jun 2007 19:19:00 +0300, Alex R. Mosteo wrote:

>> a) is there something in the ARM that prevents an equivalent transparent
>> optimization in the Ada side (returning the reference when it is detected
>> that the returned object is not modified)?
> 
> No [*], but a way to help the compiler to know what you wanted is:
> 
>    declare
>       Item : Element renames Get (Collection, Key);
>                  -- Please, don't make new objects, if you can
>    begin
>       ... -- Use Item

And this gives me another question: is there any guarantee that renaming
will avoid multiple calls, or implementation advice in this direction? I've
tried to quickly find the answer in 8.5.4 but I guess I'm not specially
suited for ARM reading today, since I don't see it clearly.