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From: eachus@spectre.mitre.org (Robert I. Eachus)
Subject: Re: Elaboration order
Date: 1996/03/20
Message-ID: <EACHUS.96Mar19192115@spectre.mitre.org>#1/1
X-Deja-AN: 143277227
references: <314701A1.469D@lfwc.lockheed.com> <Do8JDv.A2v@world.std.com>
organization: The Mitre Corp., Bedford, MA.
newsgroups: comp.lang.ada
Date: 1996-03-20T00:00:00+00:00
List-Id: <comp.lang.ada>

In article <314D2E1C.5C72@lfwc.lockheed.com> Ken Garlington <garlingtonke@lfwc.lockheed.com> writes:

  > In fact, in general, for all respondents to this question, if you
  > say that pragma Elaborate is _not_ needed in a particular context,
  > please cite an 83 reference.

    Can't possibly do that...  It is a halting problem issue to
determine if the elaboration order affects the final result of the
program.  (For almost all programs it won't, but it is very difficult
to prove.  Note that first you have to prove that your program never
does anything that in Ada 83 is erroneous.  The behavior of an
erroneous program often will depend on how things are layed out in
memory.)

  > I can't even find a reference that says the body can be assured of
  > the elaboration of its own spec!

   It can, because the specification of a unit is always elaborated
before the body due to the linear order of elaboration.  This applies
even to specs and bodies nested inside other units.


--

					Robert I. Eachus

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