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Path: utzoo!attcan!uunet!husc6!rutgers!gatech!gitpyr!tynor
From: tynor@pyr.gatech.EDU (Steve Tynor)
Newsgroups: comp.lang.ada
Subject: Re: Ada language revision
Message-ID: <6843@pyr.gatech.EDU>
Date: 23 Nov 88 19:41:03 GMT
References: <44449@beno.seismo.CSS.GOV> <3563@hubcap.UUCP> <7882@nsc.nsc.com> <739@marvin.cme-durer.ARPA> <7796@aw.sei.cmu.edu>
Reply-To: tynor@pyr.UUCP (Steve Tynor)
Organization: Georgia Institute of Technology
List-Id: <comp.lang.ada>

In article <7796@aw.sei.cmu.edu> dd@sei.cmu.edu (Dennis Doubleday) writes:
>
>In article <739@marvin.cme-durer.ARPA> leake@cme-durer.ARPA (Stephe Leake) writes:
>>In article <7882@nsc.nsc.com> rfg@nsc.nsc.com (Ron Guilmette) writes
>>>   then why shouldn't we be able to declare such types in the public part of
>>>   a package and then defer the full declaration until the package body?

>>What would this gain? Do you have any specific examples where this

>portability.  The declaration of a limited private type is an
>IMPLEMENTATION decision.  It doesn't belong in the specification, it
>belongs in the body.  If I'm trying to export some abstract data type

Here, here. I think the Modula 2 compromise of requiring 'opaque' types to be
pointers is adequate. This way there is enough information supplied in the
specification for code generation in client packages, but the implementation 
details are not broadcast.  Sure, the code may be slightly less efficient
(since you're forced to use a pointer), but I've rarely run into a situation
where I've wanted to create an ADT where a pointer (ok, ok, 'access
type') wasn't the natural representation anyway...

=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Progress means replacing something wrong with something more subtly wrong.
                     
    Steve Tynor
    Georgia Tech Research Institute
    tynor@gitpyr.gatech.edu