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From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Ada 2012 Constraints (WRT an Ada IR)
Date: Thu, 8 Dec 2016 09:46:39 +0100
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Date: 2016-12-08T09:46:39+01:00
List-Id: <comp.lang.ada>

On 07/12/2016 23:37, Randy Brukardt wrote:

> Of course it is a good thing to do, the alternative is to let callers call
> with anything they like (within the type system), which is obvious nonsense.
> Not everything can be described as a type (object state, for instance).

Sure, but if you can you must. And in this case you can.

IMO you are still confusing contracts with behavior. They are different 
for exactly the reasons you mentioned, it is impossible to describe 
everything through contracts. The object state is the part of what 
*cannot* be fully contracted. It is the program behavior when you decide 
if you call "+" or "-" with given numeric objects. The contract is that 
you can call either.

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