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From: Matthew Heaney <matthew_heaney@acm.org>
Subject: Re: Software landmines (loops)
Date: 1998/09/06
Message-ID: <m3pvda2h3e.fsf@mheaney.ni.net>#1/1
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NNTP-Posting-Date: Sun, 06 Sep 1998 00:51:48 PDT
Newsgroups: comp.lang.eiffel,comp.object,comp.software-eng,comp.lang.ada
Date: 1998-09-06T00:00:00+00:00
List-Id: <comp.lang.ada>

Charles Hixson <charleshixsn@earthlink.net> writes:

> I just feel that a tightly coupled class that doesn't really have any
> use outside the context of another class should be declared internal
> to that class...

Yes.

> ... (Ada can manage this by appropriate use of Private, but, to me,
> it's a rather tricky thing to handle this properly [I'm not sure if
> one can completely declare a class within the code body of an Ada
> file, and if you did, I think that it would have full access to the
> locally declared variables, thus expanding the bandwidth of the
> interface]).

I don't understand what you think is "tricky" about declaring one type
in the same module as another:

package P is

   type T is private;
...
private

   type U is ...;

   type T is
      record
         O : U;
         ...
      end record;

end P;


Do you object to T being able to see the representation of U?  Then just
make U private:

private

   package Q is

     type U is private;
...
   private
  
      type U is ...;

   end Q;

   type T is
      record
         O : U;
...
      end record;

end P;

        
Do you not like that U can see the representation of T?  Then make T's
representation type private:

private

   type U is ...;

   package Q is
   
     type T_Rep is private;
...
   private
   
     type T_Rep is ...;

   end Q;

   type T is new Q.T_Rep;

end P;


There's nothing hard or tricky going on here.  Just normal scope rules.