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From: crispen@eight-ball.boeing.com (crispen)
Newsgroups: comp.lang.ada
Subject: Re: Ada cost breakpoints
Message-ID: <9303291535.AA16997@eight-ball.boeing.com>
Date: 29 Mar 93 15:35:33 GMT
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Date: 1993-03-29T15:35:33+00:00
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emery@mitre-bedford.arpa  (David Emery) sez:

>The problem with this example is that it is clearly *VERY* dependent
>on Unix, and specifically BSD, semantics.  Consider what would happen
>if you tried to port this code to a non-BSD or non-Unix environment.  

Sorry to jump into this, but *I've* considered what happens -- you
write a package body that performs the equivalent functions (including
emulations and workarounds) in a non-BSD environment instead of pragma
Interface'ing in the private part of the package spec.  So what?  How
hard can that be for someone familiar with Unix and whatever proprietary
DOS you're trying to interface to?  Surely we're all familiar with
having several package bodies for a package spec by now.

>Despite the Open Systems and POSIX movements, Unix is not the only
>O.S. in the world (there's more DOS than any other O.S.) (scary, ain't it?)

Yup, it sure is, but we have hope that eventually the world will awaken
to the True Light ;-)

Seriously, Posix provides us with a standard, non-priprietary set of
OS interface semantics.  These semantics are (a) guaranteed to work
on a whole bunch of machines (or at least, if they don't work, the
vendor is obliged to admit that he has a problem); and (b) guaranteed
to change slowly, not at the whim of the vendor.  If you use Posix OS
interface semantics, you have reason to expect that your code will be
usable for a long, long time, and that changes will be relatively minor,
and announced to the world ahead of time.

It occurs to me that it might be sensible for programs to require
that all OS interfaces which are not pre-defined in the language (e.g.,
Text_IO, task stuff) be defined in Posix syntax.

What does the new AQ&S say about that?
+-------------------------------+--------------------------------------+
| Bob Crispen                   |   Who will babysit the babysitters?  |
| crispen@foxy.boeing.com       +--------------------------------------+
| (205) 461-3296                |Opinions expressed here are mine alone|
+-------------------------------+--------------------------------------+