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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Community Input for the Maintenance and Revision of the Ada
 Programming Language
Date: Tue, 12 Sep 2017 18:40:49 +0200
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Xref: news.eternal-september.org comp.lang.ada:48068
Date: 2017-09-12T18:40:49+02:00
List-Id: <comp.lang.ada>

On 2017-09-12 18:15, Egil H H wrote:
> On Tuesday, September 12, 2017 at 5:55:34 PM UTC+2, Dmitry A. Kazakov wrote:
>>
>> How is that different from:
>>
>>      package Foo is new Ada.Strings.Bounded (1000);
>>
>> ?
> 
> The difference?
> You have one string type that will always allocate 1000 Characters
> for  every variable of the type, regardless of how many the user specifies as
> max. Ada.Strings.Bounded will allocate as many as the user specifies
> as max, which is 10 in the part of your example i quoted. So you
> would use  9990% more memory...

Do you imply that Bounded_String deploys heap? I would consider such 
implementation a bug. Otherwise you will need two instances and two 
different types, which is not the intended use.

The example only illustrates how discriminants work with assignment and 
components.

> And again, how did you choose 1000? How do you know that will be
> enough for all users of your string type?

This is why Bounded_String are not used. The problem space almost never 
provides any upper bound. So the bound is an implementation constraint 
and thus a premature optimization of worst kind.

> Or do you copy/paste the
> string type every time you need a new max length?

Sure, this what generic packages basically are, dressed up macros.

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de