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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Subject: Re: MI is sloppy
Newsgroups: comp.lang.ada
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Date: Fri, 12 Dec 2008 12:15:30 +0100
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Date: 2008-12-12T12:15:30+01:00
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On Fri, 12 Dec 2008 11:50:43 +0100, Georg Bauhaus wrote:

> Dmitry A. Kazakov schrieb:

>> To me it is exactly same. The precondition not to be in a subtype is
>> equivalent to disallowing the operations specific to that subtype. Unless
>> precondition is treated as a constraint check with Constraint_Error
>> propagated. In the latter case Get is merely an overriding by the body
>> 
>> begin
>>    raise Constraint_Error;
>> end;
>> 
>> Not very exciting to me.
> 
> If you have an ambitious compiler, it might reach out,
> at compile time, for objects whose behavior is then known
> to be constrained by membership in a then known specific
> subtype.

... and then inline raising Constraint_Error. Great!

Constraint_Error propagation is the contracted behavior. You have signed
that contract, enjoy it.

Ambitious is not to be always forced to such contracts...

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