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From: eachus@spectre.mitre.org (Robert I. Eachus)
Subject: Re: Elaboration order
Date: 1996/03/22
Message-ID: <EACHUS.96Mar21191632@spectre.mitre.org>#1/1
X-Deja-AN: 143620277
references: <314701A1.469D@lfwc.lockheed.com> <Do8JDv.A2v@world.std.com>
organization: The Mitre Corp., Bedford, MA.
newsgroups: comp.lang.ada
Date: 1996-03-22T00:00:00+00:00
List-Id: <comp.lang.ada>

In article <emery-1903962048300001@line130.nwm.mindlink.net> emery@grebyn.com (David Emery) writes:

  > Of course, there wasn't time to type in the program so Eachus scribbled
  > it down on the side of an old printout, which he has subsequently
  > lost :-) :-) 

   I did NOT, I actually threw it at a couple of Ada 80 compilers to
see what happened, but the compiles never finished. :-(  When Ada 83
compilers came along, they produced code which just sat there burning
cycles, and never got to the main program. (If there was a non-trivial
solution to A**N + B**N = C**N for N > 2, the program would eventually
raise Program_Error.  Since it was using an arbitrary precision
arithmetic package, it would probably have raised Storage_Error
eventually, but I never ran it that long.)

   However, the Ada 80 program that really got me in trouble was the
one that showed a flaw in one implementor's approach to elaboration of
accept entries.  With a pair of nested accepts for the same entry with
an unconstrained array parameter, I showed just what a bad an idea
that implemetation was.  Ada 83 and Ada 95 both have a prohibition of
nested accept statements for the same entry as a result.

    As a result I made a vow NEVER to put code on a blackboard or
overhead if I don't want people actually compiling it.

--

					Robert I. Eachus

with Standard_Disclaimer;
use  Standard_Disclaimer;
function Message (Text: in Clever_Ideas) return Better_Ideas is...