Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!mcsun!cernvax!cui!anders
From: anders@cui.unige.ch (BJORNERSTEDT Anders)
Newsgroups: comp.object
Subject: Re: object-oriented this, that, and the other thing
Message-ID: <443@cui.unige.ch>
Date: 9 Nov 89 08:01:01 GMT
References: <2426@umbc3.UMBC.EDU> <190@ark1.nswc.navy.mil> <1561@novavax.UUCP> <76915@linus.UUCP> <984@castle.ed.ac.uk> <1959@tukki.jyu.fi>
Reply-To: anders@cuisun.unige.ch
Organization: University of Geneva, Switzerland
Lines: 32

In article <1959@tukki.jyu.fi> sakkinen@jytko.jyu.fi (Markku Sakkinen) SAKKINEN@FINJYU.bitnet (alternative) writes:
>In article <984@castle.ed.ac.uk> nick@lfcs.ed.ac.uk (Nick Rothwell) writes:
>-That doesn't help (does it?). A number languages have abstract data types,
>-which have been around for longer than OOP.
>
>OOP began with Simula 67 around 1967, but Simula had no 'abstract data type'
>concept (it has encapsulation facilities today).
>Has there really been some programming language with ADT's before 1967?

Yes. I think the simula-67 common base language definition already had the
class concept, but not the HIDDEN & PROTECTED features.
This means that you could construct and use ADT's using the class concept,
but could not prevent other programmers from poking at internal representation.
In fact the way I had understood the "history of concepts" is that the idea
of ADT's emerged in the 70's and evolved (in part not entirely) from one way
of using the simula class concept. 

The paper:

     B.H. Liskov and S. Zilles, "Programming  with  abstract
     data types," ACM SIGPLAN Notices, vol. 9, 1974.

makes a REF to Simula.

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