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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Possible to recover default value of scalar type?
Date: Wed, 16 Dec 2020 18:43:56 -0600
Organization: JSA Research & Innovation
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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
news:rr9p04$17qd$1@gioia.aioe.org...
> On 2020-12-15 02:26, Randy Brukardt wrote:
>> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message
>
>>>     Put_Line (String (1..10)'Default_Value); -- print garbage
>>
>> The above isn't a legal attribute prefix in any case (can't slice a 
>> type).
>
> I mean a subtype.
>
>> And you don't need to because this is clearly an aggregate (which is 
>> legal
>> in Ada 2012):
>>      Put_Line (String'(1..10 => <>)); -- print garbage
>
> Yes, I would prefer the box notation too. However having a proper name 
> would has some advantages too:
>
>    subtype S is T range T'Default_Value - 100..T'Default_Value + 100;

If box was generally allowed, you could qualify it to get this effect:

    subtype S is T range T'(<>) - 100 .. T'(<>) + 100; -- Not Ada, but 
should be IMHO. :-)

and it's shorter, too. Of course, if T doesn't have a default value, neither 
of the above is a good idea. :-)

                         Randy.