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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: Wed, 13 Sep 2017 09:24:53 +0200
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Xref: news.eternal-september.org comp.lang.ada:48096
Date: 2017-09-13T09:24:53+02:00
List-Id: <comp.lang.ada>

On 12/09/2017 21:58, Egil H H wrote:
> On Tuesday, September 12, 2017 at 9:14:50 PM UTC+2, Dmitry A. Kazakov wrote:
>>>
>>> Ah, so yo want to give up type safety... those are different types,
>>> instantiated for different purposes.
>> Sure, like
>>
>>      X : String (1..1000);
>>      Y : String (1..10);
>>
> 
> You still can't do
> X := Y;

Of course I can it is the same type.

> so why would you expect Bounded_String to behave that way?

Because the contracts of ":=" of fixed- and variable-length strings are 
different.

Fixed-length string assignment cannot change length, as the type name 
suggests. So the contract is that if the lengths are different 
Constraint_Error is propagated.

For bounded-length strings the contract is that the length may not 
exceed the bound. So the contract is that Constraint_Error to propagate 
only then.

For unbounded-length strings the contract is no Constraint_Error at all, 
but Storage_Error to propagate when it is impossible to assign.

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