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From: arny@wayback.UUCP (Arny B. Engelson)
Newsgroups: net.lang.ada
Subject: Re: pragmas, validation and garbage collection
Message-ID: <981@wayback.UUCP>
Date: Fri, 3-Oct-86 10:33:07 EDT
Article-I.D.: wayback.981
Posted: Fri Oct  3 10:33:07 1986
Date-Received: Tue, 7-Oct-86 23:40:46 EDT
References: <980@wayback.UUCP>
Organization: AT&T Bell Labs, Whippany, NJ
Keywords: validated compiler doesn't implement required pragma
Summary: Answers to the questions
List-Id: <comp.lang.ada>


   In article 1080 I asked a question about validation, pragma implementation,
and garbage collection.  I was contacted personally by someone who was
involved in the development of the compiler (and the storage manager itself),
and thought I'd summarize the info here.

   It seems the documentation I had on the compiler was DRAFT documentation,
which as we all know eventually bears no resemblance to the real product.
Although the documentation speaks as if the compiler already has an
automatic garbage collector, it is a feature slated for later development.
When (and if) this feature is implemented, I am assured that some form of
control over its operation (probably via a library package) will be provided.
Until then, I just deallocate everything manually (Unchecked_Deallocation).
   As for validating without implementing pragma Controlled, the compiler does
recognize it, but issues a "pragma ignored" message.  Supposedly, this is
"implementing" it, whereas barfing on the pragma during compilation is
unacceptable.
   (Personally, I feel all compilers should actually perform the desired task
specified by the pragma, or at least provide alternate means of control (such
as the previously mentioned library package). )

   A useful suggestion this person made to me was to convert the different
access types all to a single access type for storage in the queue, instead
of converting them to integer values.  This way I am assured the memory won't
be reclaimed and I am still storing a pointer type.  Although I haven't tested
this yet, it seems like a good idea.

   Finally, for those of you who believe bypassing Ada's strong typing is a
cardinal sin:  I don't like the idea either, but sometimes it IS a useful
thing to do.


Arny Engelson
...bonnie!wayback!arny