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Date: Fri, 12 Dec 2008 13:15:35 +0100
From: Georg Bauhaus <rm.dash-bauhaus@futureapps.de>
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Subject: Re: MI is sloppy
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Date: 2008-12-12T13:15:36+01:00
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Dmitry A. Kazakov schrieb:

>> 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.

But the compiler informs you that Constraint_Error will
be raised if your program is such that it will be raised.
Anything wrong with correcting the program?

Deriving another type, even if not sufficiently different
from the original to warrant a type, is another formal
way to trigger the same effect on the programmer, at compile
time: "There is something odd about your program".


If we wanted more of the minor differences covered
by type hierarchies, we might end up with a Qi type
system... For Ada?