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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: Press Release - Ada 2012 Language Standard Approved by ISO
Date: Wed, 26 Dec 2012 19:17:22 -0600
Organization: Jacob Sparre Andersen Research & Innovation
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Date: 2012-12-26T19:17:22-06:00
List-Id: <comp.lang.ada>

"Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de> wrote in message 
news:1drh1q1ln2dfh$.a9hwlg01fjfy.dlg@40tude.net...
...
> In the first step I would rather prefer means to declare user-defined
> operations pure, context-dependent pure, compile-time evaluated etc. This
> would be more universal than mere predicates, and "proper" predicates 
> would
> require that stuff anyway. An alternative, letting the compiler/vendor to
> deduce such properties, is IMO unrealistic (an undecidable problem, I
> think).

Some of us wanted such capabilities in Ada 2005, but there has always been a 
strong contengent of people who do not believe in having these properties 
checked by the implementation. These misguided people are opposed by an 
equally strong group that thinks that declaring unchecked properties would 
lead to making programs less safe in the case when these properties are a 
lie (which is easy to do by mistake, especially when inheritance is 
involved).

I was also hoping to have these properties be used for task-safety as well 
(truly pure functions are automatically task-safe so long as the parameters 
are different) -- but those who think "memo functions" are important to 
allow as pure bollix up the works.

For Ada 2012, we tried an end run involving proper global in/out 
properties -- but it just got too complicated and we didn't finish it. (I 
understand that some of the tools AdaCore is working on use the proposed 
global in/out properties, so there is some hope that it will make it into 
Ada in the future).

                               Randy.