From: collins@cs.wm.edu (Bob Collins)
Subject: Re: Why both "with" and "use"?
Date: 1999/02/14
Date: 1999-02-14T00:00:00+00:00 [thread overview]
Message-ID: <collins-1402991015000001@cx832447-a.nwptn1.va.home.com> (raw)
In-Reply-To: 7a6jho$nkv$1@remarQ.com
In article <7a6jho$nkv$1@remarQ.com>, "Pat Rogers"
<progers@NOclasswideSPAM.com> wrote:
> Yes, the package isn't part of the type itself, but let's go back for
> a moment to the definition I gave of an ADT: "a set of legal
> operations (the "primitives") and legal values, and little else." It
> is the "little else" that packages provide, and IMHO and ADT without
> that aspect is not an ADT. We're in agreement overall, of course, but
> I think it is important to stress that, in addition to the demarcation
> of the primitives, as you've said above, the encapsulation of the
> type's representation is an essential aspect of an ADT. Without
> packages, we have no encapsulation, no information hiding.
In the Guttag-Horning-Liskov formulations of the algebraic
specifications of ADTs, errors were important values. The
Ada package allows errors in ADTs very naturally, as exceptions
declared inside the package. Every stack ADT need an Empty_Stack
exception declaration for completeness as an ADT and possibly
a Stack_Overflow exception declaration as a practical convenience.
These are the kinds of things that are more than the "little else"
mentioned above. Also, when the TOI (type of interest) in each of
two type algebras is a supporting type in the other, it is
programmatically convenient to include both ADTs in the same
package. In this thread, we've already seen an example of a structure
and its iterator in the same package.
--
Bob Collins <mailto:collins@cs.wm.edu> <http://ratbert.cs.wm.edu>
next prev parent reply other threads:[~1999-02-14 0:00 UTC|newest]
Thread overview: 55+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-02-13 0:00 Why both "with" and "use"? Mike Silva
1999-02-13 0:00 ` Corey Minyard
1999-02-13 0:00 ` Matthew Heaney
1999-02-13 0:00 ` Tom Moran
1999-02-14 0:00 ` Matthew Heaney
1999-02-13 0:00 ` bill
1999-02-14 0:00 ` Matthew Heaney
1999-02-14 0:00 ` dewar
1999-02-14 0:00 ` dewar
1999-02-16 0:00 ` Samuel Mize
1999-02-17 0:00 ` Jean-Pierre Rosen
1999-02-18 0:00 ` dennison
1999-02-18 0:00 ` robert_dewar
1999-02-19 0:00 ` dennison
1999-02-19 0:00 ` Robert I. Eachus
1999-02-19 0:00 ` robert_dewar
1999-02-23 0:00 ` Robert I. Eachus
1999-02-19 0:00 ` Brian Hanson
1999-02-19 0:00 ` robert_dewar
1999-02-19 0:00 ` bourguet
1999-02-19 0:00 ` robert_dewar
1999-02-19 0:00 ` Matthew Heaney
1999-02-19 0:00 ` dennison
1999-02-19 0:00 ` robert_dewar
1999-02-19 0:00 ` Ada multiple string personalities. why so many? mike
1999-02-19 0:00 ` Tom Moran
1999-02-19 0:00 ` Mike Silva
1999-02-22 0:00 ` Brian Hanson
1999-02-19 0:00 ` robert_dewar
1999-02-19 0:00 ` Why both "with" and "use"? dennison
1999-02-19 0:00 ` robert_dewar
1999-02-18 0:00 ` robert_dewar
1999-02-18 0:00 ` Jean-Pierre Rosen
1999-02-18 0:00 ` robert_dewar
1999-02-19 0:00 ` Jean-Pierre Rosen
1999-02-17 0:00 ` Matthew Heaney
1999-02-17 0:00 ` Jean-Pierre Rosen
1999-02-17 0:00 ` dennison
1999-02-17 0:00 ` Nick Roberts
1999-02-17 0:00 ` Samuel Mize
1999-02-13 0:00 ` mike
1999-02-13 0:00 ` Pat Rogers
1999-02-13 0:00 ` bill
1999-02-13 0:00 ` Matthew Heaney
1999-02-13 0:00 ` Pat Rogers
1999-02-13 0:00 ` Matthew Heaney
1999-02-13 0:00 ` bill
1999-02-14 0:00 ` Pat Rogers
1999-02-14 0:00 ` Bob Collins [this message]
1999-02-14 0:00 ` Pat Rogers
1999-02-16 0:00 ` Samuel Mize
1999-02-15 0:00 ` Jean-Pierre Rosen
1999-02-15 0:00 ` Ed Falis
1999-02-16 0:00 ` Jean-Pierre Rosen
1999-02-15 0:00 ` Jean-Pierre Rosen
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