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Date: 16 Sep 92 17:47:15 GMT
From: agate!linus!linus.mitre.org!mwvm.mitre.org!M19481@ucbvax.Berkeley.EDU
Subject: Re: Using Global Variables
Message-ID: <16864C1E7.M19481@mwvm.mitre.org>
List-Id: <comp.lang.ada>

In article <1992Sep16.152620.9286@nosc.mil>
sampson@nosc.mil (Charles H. Sampson) writes:
 
>
>In article <15390@suns5.crosfield.co.uk> pdg@crosfield.co.uk (paul goffin)
>writes (in an article on Ada compiler pricing):
>
>>So what did I mean by cost?  Well, apart from the training costs
>>and the cost of setting up development systems that act>>Ada, (New compiler d
riving scripts, new way of addressing hardware,
>>new way of managing "global variables" - Yes, nasty as they are,
>>you do sometimes have to use global variables in the real world!)
>>there was a nasty shock in the price of the compilers.
>
>     I'd like to hear more about this need to use global variables in
>the real world, from Mr. Goffin and anyone else.  I can't remember the
>last time I used one in an Ada project, and I think what I do is pretty
>real world stuff.  (Well, I do contract to the U. S. Navy, but that's
>close.)
>
>                                Charlie
 
The main reason I've heard used to justify the use of global variables is
performance of a real-time system.  The argument goes that the overhead of
parameter passing is just too high to meet the performance requirements on
the target machine (which cannot be changed), hence global variables.  Now
you may argue that the target machine should have been chosen more wisely,
or the choice delayed until after the software was totally developed so as
to be able to pick the right size machine -- but I imagine that that's what
Mr. Goffin had in mind when he used the term "real world."
 
David - dhite@mitre.org