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From: jwierzbo@hercii.lasc.lockheed.com (Joe Wierzbowski)
Subject: Re: Elaboration order
Date: 1996/03/16
Message-ID: <1996Mar16.213029.24934@enterprise.rdd.lmsc.lockheed.com>#1/1
X-Deja-AN: 143191053
sender: news@enterprise.rdd.lmsc.lockheed.com (News Administrator)
references: <314829CD.4FA9@lfwc.lockheed.com>
organization: Lockheed Martin Aeronautical Systems
reply-to: jwierzbo@hercii.lasc.lockheed.com
newsgroups: comp.lang.ada
Date: 1996-03-16T00:00:00+00:00
List-Id: <comp.lang.ada>

In article 4FA9@lfwc.lockheed.com, Ken Garlington <GarlingtonKE@lfwc.lockheed.com> () writes:
>   < snip >
> 
> So what does this mean in the following case:
> 
> package Another_Example is
> 
>   function Initial_Value return Integer;
> 
> end;
> 
> package body Another_Example is
> 
>   function Initial_Value return Integer is begin return 0; end;
> 
> end;
> 
> with Another_Example;
> package Use_Example is
> 
>   X : Integer := Another_Example.Initial_Value;
> 
> end;
> 
> Can I get a Program_Error on the initialization of X? If so,
> it would seem like there would need to be a pragma
> Elaborate for nearly every reference to every package
> exporting a subprogram!

  Yes, you can get Program_Error on the initialization of X.

  The important point here for Ada 83 is that this requirement
  refers to declarative regions.  So your choices are:
  1) Add a pragma Elaborate for each subprogram called during a 
     declarative region or
  2) Don't make initial assignments using subprogram calls in a
     declarative region.  This is a common mistake, so much so
     that it may be worth adding a restriction against doing so 
     in a coding standard.  I can tell you that it's almost always
     the first thing to bite you during integration; there's always
     someone who has an elaboration order problem.  

  Another thing to note here is that Ada 95 provides convenient
  ways of elaborating every required package (See Robert Duff's
  posting).