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From: Ken Garlington <garlingtonke@lfwc.lockheed.com>
Subject: Re: Elaboration order
Date: 1996/03/15
Message-ID: <314972FC.3F86@lfwc.lockheed.com>#1/1
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references: <314829CD.4FA9@lfwc.lockheed.com>
 <DoBAMB.GGs.0.-s@inmet.camb.inmet.com>
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organization: Lockheed Martin Tactical Aircraft Systems
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Date: 1996-03-15T00:00:00+00:00
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Tucker Taft wrote:
> 
> You only need a pragma Elaborate[_All](pkg) if you call a subprogram
> from "pkg" as part of the *elaboration* of some other package.
> 
> If the calls only appear in subprogram bodies, rather than at
> the package level, you shouldn't have any problem.

OK. Keeping in mind that I need the answer in terms of Ada 83, then this
is what I think I've heard so far:

1. If, in a package specification, I refer to something in another
package specification that is not completely defined in the other spec,
I need a pragma Elaborate. "Something" can include:

  - any case where I need the sequence_of_statements in the package
    body to run prior to the use of the something, such as a variable
    in the spec which is set in the sequence_of_statements. This case,
    I think I always understood.

  - any subprogram (since, otherwise, I could get a Program_Error); although
    I guess it would have to be a function. This case, I didn't understand.

2. On the other hand, if I refer to a subprogram within another subprogram
   body, I don't have to use pragma Elaborate. Is there a spec reference for
   this? What about referring to a subprogram elsewhere in a package body?
   What about the sequence_of_statements case above?

I'm trying to write up an explanation of this issue for our users, since
I don't think we understood the extent to which pragma Elaborate was needed.
Any assistance in this area in the immediate future would be appreciated.

> 
> -Tucker Taft   stt@inmet.com   http://www.inmet.com/~stt/
> Intermetrics, Inc.  Cambridge, MA  USA