Path: utzoo!mnetor!uunet!husc6!bbn!rochester!PT.CS.CMU.EDU!IUS3.IUS.CS.CMU.EDU!ralphw
From: ralphw@IUS3.IUS.CS.CMU.EDU (Ralph Hyre)
Newsgroups: comp.lang.misc
Subject: Re: From Modula to Oberon
Message-ID: <1217@PT.CS.CMU.EDU>
Date: 24 Mar 88 20:59:56 GMT
References: <2827@enea.se> <1557@pasteur.Berkeley.Edu> <3764@bloom-beacon.MIT.EDU> <1130@PT.CS.CMU.EDU>
Sender: netnews@PT.CS.CMU.EDU
Organization: Carnegie-Mellon University, CS/RI
Lines: 33

In article <1130@PT.CS.CMU.EDU> edw@IUS1.CS.CMU.EDU (Eddie Wyatt) writes:
>> 
>> I wish they had put iterators in Ada. C provides a general linear
>> iterator, but in CLU you can iterate through a tree or anything else...
....
>		***This is not a flame against the author.***
>
>   When will people learn, data abstraction is not a programming
>language or type of programming language, it is a programming
>methodology.
> 
>  In particular if you want generalized iteration say in C, its
>a simple matter of defining an iteration function for that particular
>data type.
I agree with your first point, but it's not so simple to do things
in a language that wasn't designed to support them cleanly.  The Guttag &
Liskov book spends a chapter or so discussing doing data abstraction
in Turbo Pascal.
I'd rather spend my time writing code than worrying about how to map my
programming methodology onto a language that doesn't support it neatly.

When I make my own mapping, it also makes it harder for someone else to
come along later and understand what I did, unless I document my
techniques and experiences.

[I must admit to some bias here, I feel much more productive using CLU
than C.  Other than interoperability with certain existing code, I can't
see any reason to use C when CLU is available.]
-- 
					- Ralph W. Hyre, Jr.

Internet: ralphw@ius2.cs.cmu.edu    Phone:(412)268-{2847,3275} CMU-{BUGS,DARK}
Amateur Packet Radio: N3FGW@W2XO, or c/o W3VC, CMU Radio Club, Pittsburgh, PA