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From: jsa@alexandria.organon.com (Jon S Anthony)
Subject: Re: Separation of IF and Imp: process issue?
Date: 1997/08/31
Message-ID: <JSA.97Aug31145336@alexandria.organon.com>#1/1
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References: <33E9ADE9.4709@flash.net> <5u3dne$c20@gcsin3.geccs.gecm.com>
 <34057115.D4D7713@stratasys.com> <x7vd8myyrzx.fsf@pogner.demon.co.uk>
 <EFqyG7.67v@ecf.toronto.edu>
Distribution: world
Organization: PSINet
Newsgroups: comp.object,comp.software-eng,comp.lang.ada,comp.lang.eiffel
Date: 1997-08-31T00:00:00+00:00
List-Id: <comp.lang.ada>


In article <EFqyG7.67v@ecf.toronto.edu> doylep@ecf.toronto.edu (Patrick Doyle) writes:

> IMO, having separate interface and implementation files for the
> same package simply reinforces the somewhat antiquated notion
> that an implementation has only one interface.  In fact, by
> Ada, they must have a one-to-one correspondence.

Patrick,

If you are going to complain about something at least get the
complaint right before going off half cocked.  With child packages you
can give an implementation as many completely different interfaces as
you like.  IOW, your "in fact" is not.


package P is
...interface
private
...impl representation
end P;

package P.C1 is
...new interface for P's impl
end P.C1;

package P.C2 is
...yet another interface for P's impl
end P.C2;

etc.


> It has been pointed out that abstract (ie. deferred) classes can
> do the same thing with greater flexibility.

Again - get it right.  Abstract classes are analogous to abstract
types in Ada, NOT packages.


/Jon
-- 
Jon Anthony
OMI, Belmont, MA 02178, 617.484.3383 
"Nightmares - Ha!  The way my life's been going lately,
 Who'd notice?"  -- Londo Mollari