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From: Robert Dewar <robert_dewar@my-deja.com>
Newsgroups: comp.lang.ada
Subject: Re: Ok sorry, it is just a book gives no feedback.
Date: Sat, 06 Jan 2001 20:36:48 GMT
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Date: 2001-01-06T20:36:48+00:00
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In article <86hf3c5ure.fsf@acm.org>,
  Laurent Guerby <guerby@acm.org> wrote:

> The trick is to use pragma Import in Pure units to import
> "unpure" debugging stuff without withing it.

Sshhhh! This is a secret trick that should not be revealed to
the uninitiated :-) :-)

Few Ada programmers realize what a huge hole this is in the
language (introduced in Ada 95 with the formal recognition of
Ada as a convention).

You can do all *sorts* of things by using pragma Import and
Export with convention Ada. You can completely disconnect type
checking at the subprogram call interface. You can compeltely
disconnect elaboration order checking in elaboration code etc.
You can also bypass any "silly" rules that you don't like about
what you can and cannot WITH.

I wonder whether we realized what a big hole we were creating
there. I very seldom favor absolute rules in coding standards,
so I hesitate to say *never* use convention Ada in this manner,
but for sure you have to be super careful, it is as bad or
worse than any of the unchecked interfaces in the language, and
does not clearly announce itself, since the Import can be
buried deep in the implementation code.


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