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From: schlegel@informatik.uni-rostock.de (Juergen Schlegelmilch)
Subject: Re: Real OO
Date: 1996/05/09
Date: 1996-05-09T00:00:00+00:00	[thread overview]
Message-ID: <slrn4p395h.2rc.schlegel@pella.informatik.uni-rostock.de> (raw)
In-Reply-To: Dr4538.D27@assip.csasyd.oz


On Thu, 9 May 1996 00:52:19 GMT, Don Harrison <donh@syd.csa.com.au> wrote:
> Thanks for the pointer. Have asked cecil@cs.washington.edu for more info.

Sorry, I forgot to include numbers in my pointer: The technical report is 
available as 
  University of Washington CS&E Technical Report 95-08-05
  Iowa State University CS Technical Report #95-19

It also says an earlier version appeared in the proceedings of OOPSLA'94.
 

> :the Liskov Substitution Principle,
>      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> Could you (or somone) explain what this is? Sorry, I'm a bit ignorant.

This goes back to an article:
     Liskov, Barbara. "Data Abstraction and Hierarchy."
     SIGPLAN Notices 23,5 (May 1988) pg 25.

It says that objects of a subclass must not only be structurally substitutable
(i.e. show the same interface) but also behaviourally, i.e. they have to 
accept the same set of event sequences. First of all, this means you cannot
have (single-dispatch with) covariance since this allows an object in a 
subclass to require more specific parameters. Second and more important,
the observable changes in the object must be equivalent for all sequences
of events (= method calls). --- I have to admid that I never read the 
original article from Barbara Liskov, so anyone can correct me on the
exact definition.

Regards,
  Juergen 


-- 
+-----------------------------------------------------------------------------+
 Dipl.-Inf. Juergen Schlegelmilch                 University of Rostock
 email: schlegel@Informatik.Uni-Rostock.de        Computer Science Department
 http://www.informatik.uni-rostock.de/~schlegel   Database Research Group 
 Tel: ++49 381 498 3402                           18051 Rostock 
 Fax: ++49 381 498 3404                           Germany
+-----------------------------------------------------------------------------+





  parent reply	other threads:[~1996-05-09  0:00 UTC|newest]

Thread overview: 218+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <4id031$cf9@dayuc.dayton.saic.com>
1996-03-18  0:00 ` Real OO Norman H. Cohen
1996-03-18  0:00   ` The Right Reverend Colin James III
1996-03-19  0:00     ` Norman H. Cohen
1996-03-20  0:00       ` Norman Cohen giving IBM a bad name The Right Reverend Colin James III
1996-03-20  0:00         ` Dave Retherford
1996-03-20  0:00         ` Real OO Dale Stanbrough
1996-03-21  0:00           ` Richard Pitre
1996-03-20  0:00         ` Norman Cohen giving IBM a bad name Brian & Karen Bell
1996-03-20  0:00         ` Colin James III giving humans a bad name (was Re: Norman Cohen giving IBM a bad name) David Emery
1996-03-20  0:00           ` Mark R Okern - F95
1996-03-20  0:00             ` Real OO John G. Volan
1996-03-21  0:00               ` Scott Leschke
1996-03-21  0:00                 ` Robert A Duff
1996-03-21  0:00                 ` Norman H. Cohen
1996-03-22  0:00                 ` Don Harrison
1996-03-21  0:00             ` Colin James III giving humans a bad name (was Re: Norman Cohen giving IBM a bad name) Richard A. O'Keefe
1996-03-21  0:00               ` Robert Dewar
1996-03-21  0:00         ` Norman Cohen giving IBM a bad name Kent Mitchell
1996-03-22  0:00         ` Robert Munck
1996-03-22  0:00           ` Mark Brennan
1996-03-22  0:00             ` David Curry
1996-03-23  0:00         ` Tom Reid
1996-03-21  0:00       ` Real OO Don Harrison
1996-03-21  0:00   ` Colin James III giving humans a bad name (was Re: Norman Cohen giving IBM a bad name) Ulrich Windl
1996-03-20  0:00 ` Real OO Don Harrison
1996-03-22  0:00 ` Don Harrison
1996-03-22  0:00   ` Norman H. Cohen
1996-03-26  0:00     ` Don Harrison
1996-03-26  0:00       ` Norman H. Cohen
1996-03-29  0:00         ` Don Harrison
1996-03-27  0:00       ` Thomas Beale
1996-03-28  0:00         ` Don Harrison
1996-03-22  0:00   ` Norman H. Cohen
1996-03-27  0:00     ` Don Harrison
1996-03-27  0:00       ` Norman H. Cohen
1996-03-28  0:00         ` Jacob Gore
1996-04-04  0:00         ` Don Harrison
1996-04-04  0:00           ` Robb Nebbe
1996-04-04  0:00           ` Laurent Guerby
1996-04-04  0:00           ` Tucker Taft
1996-04-04  0:00             ` Tucker Taft
1996-04-12  0:00               ` Don Harrison
1996-04-12  0:00             ` Don Harrison
1996-04-15  0:00               ` Robert I. Eachus
1996-04-19  0:00                 ` Don Harrison
1996-04-19  0:00                   ` Matt Kennel
1996-04-20  0:00                     ` Bob Hathaway
1996-04-23  0:00                     ` Don Harrison
1996-04-04  0:00           ` Jon S Anthony
1996-03-23  0:00   ` Joachim Durchholz
1996-03-26  0:00     ` Norman H. Cohen
1996-04-04  0:00       ` Don Harrison
1996-04-04  0:00         ` Jon S Anthony
1996-04-12  0:00           ` Don Harrison
1996-04-17  0:00             ` Jon S Anthony
1996-04-19  0:00               ` Don Harrison
1996-04-19  0:00                 ` Multiple Dispatch in Ada 95 (Was Re: Real OO) Brian Rogoff
1996-04-21  0:00                   ` Brian Rogoff
1996-04-19  0:00                 ` Real OO Jon S Anthony
1996-04-23  0:00                   ` Don Harrison
1996-04-24  0:00                     ` Don Harrison
1996-04-29  0:00                     ` Jon S Anthony
1996-04-30  0:00                       ` Robert Dewar
1996-04-30  0:00                         ` Amit Patel
1996-04-30  0:00                           ` Robert A Duff
1996-05-07  0:00                             ` Amit Patel
1996-05-01  0:00                           ` Norman H. Cohen
1996-05-01  0:00                             ` Colin James III (The Rt Rev'd)
1996-05-07  0:00                             ` Amit Patel
1996-04-30  0:00                         ` Robert A Duff
1996-04-30  0:00                           ` Robert Dewar
1996-05-01  0:00                             ` Richard Bielak
1996-04-30  0:00                           ` Amit Patel
1996-05-01  0:00                           ` Adam Beneschan
1996-05-02  0:00                             ` Ell
1996-05-01  0:00                         ` Don Harrison
1996-05-01  0:00                           ` David Hopwood
1996-05-03  0:00                             ` Don Harrison
1996-05-01  0:00                           ` Don Harrison
1996-05-02  0:00                             ` Robert A Duff
1996-05-03  0:00                               ` Don Harrison
1996-05-03  0:00                                 ` Robert A Duff
1996-05-06  0:00                                   ` Don Harrison
1996-05-06  0:00                                     ` Robb Nebbe
1996-05-06  0:00                                     ` Robert A Duff
1996-05-02  0:00                           ` Robert A Duff
1996-05-03  0:00                             ` Don Harrison
1996-05-10  0:00                             ` Don Harrison
1996-05-01  0:00                         ` AdaWorks
1996-05-08  0:00                         ` Joachim Durchholz
1996-05-03  0:00                       ` Don Harrison
1996-05-03  0:00                         ` Dave Fitch
1996-05-07  0:00                         ` Jon S Anthony
1996-04-30  0:00                     ` Jon S Anthony
1996-05-01  0:00                       ` Matt Kennel
1996-05-03  0:00                         ` Don Harrison
1996-05-02  0:00                       ` Don Harrison
1996-05-02  0:00                         ` Robert I. Eachus
1996-05-02  0:00                         ` Jon S Anthony
1996-05-03  0:00                           ` Don Harrison
1996-05-06  0:00                             ` Jon S Anthony
1996-05-06  0:00                         ` Jon S Anthony
1996-05-06  0:00                       ` Don Harrison
1996-05-06  0:00                         ` Don Harrison
1996-05-07  0:00                         ` Jon S Anthony
1996-05-13  0:00                           ` Don Harrison
1996-05-09  0:00                         ` Jon S Anthony
1996-04-30  0:00                     ` Joachim Durchholz
1996-04-19  0:00                 ` Multiple Dispatch in Ada 95 (Was Re: Real OO) Robert I. Eachus
1996-04-20  0:00                 ` Brian Rogoff
1996-04-21  0:00                   ` Robert A Duff
1996-04-24  0:00                 ` Real OO Joachim Durchholz
1996-05-01  0:00                   ` Matt Kennel
1996-05-02  0:00                     ` Don Harrison
1996-05-07  0:00                   ` Joachim Durchholz
1996-05-08  0:00                   ` Jon S Anthony
1996-05-09  0:00                   ` Robert I. Eachus
1996-04-30  0:00                 ` Joachim Durchholz
1996-05-08  0:00                   ` Joachim Durchholz
1996-05-10  0:00                   ` Jon S Anthony
1996-04-30  0:00                 ` Jon S Anthony
1996-05-03  0:00                   ` Don Harrison
1996-05-07  0:00                     ` Jon S Anthony
1996-05-02  0:00                 ` Jon S Anthony
1996-05-06  0:00                 ` Jon S Anthony
1996-04-08  0:00         ` Norman H. Cohen
1996-04-08  0:00           ` Robert A Duff
1996-04-09  0:00             ` Norman H. Cohen
1996-04-10  0:00           ` Don Harrison
1996-04-11  0:00           ` Jacob Gore
1996-04-12  0:00           ` Don Harrison
1996-04-12  0:00             ` Jacob Gore
1996-04-16  0:00               ` Don Harrison
1996-04-12  0:00           ` Don Harrison
1996-04-12  0:00             ` Jon S Anthony
1996-04-13  0:00               ` Robert A Duff
1996-04-12  0:00             ` Matt Kennel
1996-04-15  0:00               ` Don Harrison
1996-04-16  0:00             ` Jon S Anthony
1996-04-09  0:00         ` Valery CROIZIER
1996-04-09  0:00         ` Jon S Anthony
1996-04-09  0:00       ` Joachim Durchholz
1996-05-02  0:00       ` Joachim Durchholz
1996-05-05  0:00         ` Robert A Duff
1996-05-05  0:00           ` Robert Dewar
1996-05-06  0:00         ` Norman H. Cohen
1996-05-07  0:00           ` Ada terminology (was Re: Real OO) David Hopwood
1996-05-07  0:00             ` The Right Reverend Colin James III
1996-05-07  0:00             ` Tucker Taft
1996-05-07  0:00               ` The Right Reverend Colin James III
1996-05-08  0:00               ` bill.williams
1996-05-07  0:00             ` Dave Jones
1996-05-07  0:00           ` Real OO Don Harrison
1996-05-07  0:00             ` Jon S Anthony
1996-05-08  0:00               ` Don Harrison
1996-05-08  0:00             ` Norman H. Cohen
1996-05-08  0:00               ` Robert A Duff
1996-05-10  0:00                 ` Matt Kennel
1996-05-10  0:00                   ` Robert A Duff
1996-05-14  0:00                     ` Matt Kennel
1996-05-15  0:00                       ` Robert A Duff
1996-05-07  0:00         ` Amit Patel
1996-05-07  0:00           ` The Right Reverend Colin James III
1996-05-08  0:00           ` Don Harrison
1996-05-08  0:00             ` Juergen Schlegelmilch
     [not found]               ` <Dr4538.D27@assip.csasyd.oz>
1996-05-09  0:00                 ` Richard Riehle
1996-05-10  0:00                   ` Tucker Taft
1996-05-13  0:00                     ` Don Harrison
1996-05-13  0:00                       ` Tucker Taft
1996-05-14  0:00                         ` Don Harrison
1996-05-14  0:00                           ` Steve Tynor
1996-05-14  0:00                             ` Robert A Duff
1996-05-15  0:00                             ` Don Harrison
1996-05-14  0:00                           ` Robert A Duff
1996-05-15  0:00                           ` Steve Tynor
1996-05-15  0:00                             ` Robert A Duff
1996-05-16  0:00                           ` James McKim
1996-05-18  0:00                             ` Matt Kennel
1996-05-20  0:00                               ` James McKim
1996-05-22  0:00                                 ` Matt Kennel
1996-05-14  0:00                         ` Roger Browne
1996-05-14  0:00                         ` Joachim Durchholz
1996-05-15  0:00                         ` Alexander Kjeldaas
1996-05-15  0:00                         ` Steve Tynor
1996-05-19  0:00                         ` Piercarlo Grandi
1996-05-14  0:00                   ` James McKim
1996-05-15  0:00                     ` Juergen Schlegelmilch
1996-05-09  0:00                 ` Juergen Schlegelmilch [this message]
1996-05-20  0:00               ` Joachim Durchholz
1996-05-07  0:00       ` Joachim Durchholz
1996-05-09  0:00         ` Don Harrison
1996-05-09  0:00           ` Jon S Anthony
1996-05-09  0:00           ` Joachim Durchholz
1996-04-02  0:00     ` Detecting type mismatch at compile time (was Re: Real OO) Robert I. Eachus
1996-04-03  0:00       ` Richard Bielak
1996-04-04  0:00       ` Don Harrison
1996-03-28  0:00   ` Real OO Joachim Durchholz
1996-03-29  0:00     ` Norman H. Cohen
1996-03-30  0:00       ` John G. Volan
1996-03-26  0:00 ` Jon S Anthony
1996-03-29  0:00 ` Joachim Durchholz
1996-04-04  0:00   ` Don Harrison
1996-04-04  0:00     ` Steve Tynor
1996-04-08  0:00       ` Norman H. Cohen
1996-04-09  0:00         ` Matt Kennel
1996-04-04  0:00     ` Dominique Colnet
1996-04-08  0:00     ` Matt Kennel
1996-04-09  0:00       ` Norman H. Cohen
1996-04-09  0:00     ` Robert C. Martin
1996-04-10  0:00     ` J. Kanze
1996-05-02  0:00 Bob Crispen
     [not found] <DoDLr7.JDB@world.std.com>
     [not found] ` <4if7s5$bfk@ra.nrl.navy.mil>
     [not found]   ` <DoDqH4.29v@world.std.com>
1996-03-26  0:00     ` AdaWorks
1996-03-29  0:00   ` Brian Rogoff
     [not found] <4hneps$1238@watnews1.watson.ibm.com>
     [not found] ` <Do3F1K.4xG@assip.csasyd.oz>
     [not found]   ` <4i455s$ijq@watnews1.watson.ibm.com>
1996-03-15  0:00     ` Don Harrison
     [not found]       ` <DoBH80.9u9@world.std.com>
1996-03-15  0:00         ` Mark A Biggar
1996-03-15  0:00         ` Richard Pitre
1996-03-16  0:00     ` Des  Kenny
     [not found] <JSA.96Mar13143956@organon.com>
1996-03-15  0:00 ` Don Harrison
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