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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: About task-safeness
Date: Wed, 2 Feb 2011 20:44:34 -0600
Organization: Jacob Sparre Andersen Research & Innovation
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Date: 2011-02-02T20:44:34-06:00
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"mockturtle" <framefritti@gmail.com> wrote in message 
news:06ecb5ab-a9e5-4a5d-9370-6bbe137d3693@glegroupsg2000goo.googlegroups.com...
...
>(For example, a package defining some type of object could keep the number 
>of allocated
>objects, so it can give to each object a unique ID.)  If such a package was 
>used  by two
>different tasks, and the counter was not protected, obscure bugs can arise. 
>This type of
>structure maybe is not very recommended, but it happens... :-(

Note that "protection" may simply be declaring the object Atomic. Presuming 
the compiler supports that, there isn't a problem with multiple tasks 
accessing the same counter. (The main problem with small objects is 
compilers that get too helpful and optimize the unoptimizable.)

...
>Consider, for example, the Ordered_Maps package.  That package is not Pure 
>(it cannot be,
>since it would prevent the use of named access types), so how can I be 
>granted that the package
>does not have some "hidden" and unprotected state?

Hidden and truely unprotected would violate the RM, as noted by others. But 
hidden and Atomic is fine (the Janus/Ada containers will use counters this 
way to detect dangling cursors).

                              Randy.