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From: dale@cs.rmit.edu.au (Dale Stanbrough)
Subject: Re: Private Children
Date: 1999/06/21
Message-ID: <dale-2106991002230001@dale.cs.rmit.edu.au>#1/1
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References: <m3bteacxb8.fsf@mheaney.ni.net>
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Newsgroups: comp.lang.ada
Date: 1999-06-21T00:02:32+00:00
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Matthew Heaney wrote:

" Can a public child package with its private sibling?
  
  According to my compiler, the answer is no.  When I try to compile the
  unit below (P.C2), I get the following error message:
  
  gcc -c -gnatc /home/matt/p-c2.ads
  p-c2.ads:1:06: current unit must also be private descendant of "P"
  
  
  Public child P.C2 only uses the entity provided by its private sibling
  P.C1 in its private region.  What is the rationale for making this
  illegal?"


Tucker Taft once explained that this allows for "compilation privacy"
(my description). This guarentees that if a private package spec changes,
you don't have to do any recompilation of any public packages (just
relinking).

Personally I don't care for it, and would have much preferred
"implementation privacy" where changes to a spec of a private
package could still mean that public clients may have to be
recompiled, but not updated in any other way.

Dale