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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Ada case-statement
Date: Fri, 16 Mar 2018 18:49:38 -0500
Organization: JSA Research & Innovation
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Date: 2018-03-16T18:49:38-05:00
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"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
news:p8g0om$1gpe$1@gioia.aioe.org...
> On 15/03/2018 23:20, Randy Brukardt wrote:
>> "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message
>> news:p8dbcp$11bc$1@gioia.aioe.org...
>
>>> I don't see how giving a name could add anything to the semantics. Each
>>> alternative exhaustively defines a constraint. No reason to contaminate
>>> the name space.
>>
>> How does
>>       when Today: Thurs =>
>> exhaustively define anything? It just defines a constraint, but there is 
>> not
>> way to know of what. > You have to look at the selecting_expression to 
>> find
>> the type -- but it doesn't show it either.
>
> This applies to everything:
>
>    when Thurs =>
>
> What is the type of Thurs? I either know or in most cases simply do not 
> care.

You have to know, and you usually do with a commonly used enumeration. And 
at the same time it isn't as important to know - you almost never are going 
to use any overloaded operators (which often require qualifying something) 
in a case limb.

Once you have a general name for something, you can (and do) use it in many 
contexts, and then the type (and its name) become necessary: for "use type", 
for qualifications, for type conversions, and so on.

> In any case this is no change of the semantics. Today has the semantics of 
> the case statement argument. You didn't specify the type there, why should 
> you do here?

You're not declaring an object for the case selector; that's "consuming" a 
value rather than creating one. All objects should have their type defined 
directly next to the declaration.

                                         Randy.