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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 18:45:17 -0600
Organization: JSA Research & Innovation
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"Niklas Holsti" <niklas.holsti@tidorum.invalid> wrote in message 
news:i3re1oF5omrU1@mid.individual.net...
> On 2020-12-15 3:27, Randy Brukardt wrote:
>> "AdaMagica" <christ-usch.grein@t-online.de> wrote in message
>> news:570e9d30-0b33-45f0-a9fe-163cc810a770n@googlegroups.com...
>>> Dmitry A. Kazakov schrieb am Montag, 14. Dezember 2020 um 10:38:42 
>>> UTC+1:
>>>> procedure Library_Foo (Bar : Baz := Baz'Default_Value)
>>> Suppose type Baz has no default value aspect. Then a call Library_Foo
>>> without parameter would use what?
>>> A solution could be that the attribute is illegal if there is no aspect.
>>> The compiler knows.
>>
>> Not always. Never forget generics. One would hope to be able to use this 
>> on
>> generic formal types, as most of them are going to have default values 
>> (at
>> least in new code).
>
>
> The generic formal type declarations could be extended to indicate that a 
> Default_Value is required, for example:
>
>    generic
>       type T is private with Default_Value;

Sure, but more complication. We (as a group) decided it wasn't worth it. I'd 
rather extend <> anyway, and that would be allowed anywhere, much like a 
raise_expression.

                    Randy.