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From: kurt@fluke.UUCP
Newsgroups: comp.lang.misc
Subject: OOPS
Message-ID: <364@oracle.tc.fluke.COM>
Date: Thu, 29-Jan-87 22:26:35 EST
Article-I.D.: oracle.364
Posted: Thu Jan 29 22:26:35 1987
Date-Received: Sat, 31-Jan-87 06:34:12 EST
Distribution: comp.lang.misc
Organization: John Fluke Mfg. Co., Inc., Everett, WA
Lines: 26

One of the touted advantages of Smalltalk when it is called object
oriented is dynamic binding.  Specifically you can send a "foo" message
to any class.  The designer of the system insures that all relevant
objects provide a method to "foo" themselves.  Naturally, if an object
doesn't know how to "foo" itself, you get a message not understood
error.  So here's the question...What has dynamic binding bought you?
Don't you have to know pretty much what object you are sending "foo"
messages to?  Don't you have to inspect something in the object or
remember when you created an object what type it is so you know it can
receive a "foo"?  Ignore the boring case where ALL your objects know
how to "foo".  You might just as well have used a language with early
binding and inheritance (CLU, Simula, ...)  

Also, I have repeatedly heard the claim that dynamically bound languages are
"just as fast" as static languages.  OK, make me a believer.  Who says so?  I
read a paper by a guy who said LISP could be optimized to a C-like level.
In fact, he has a compiler that eliminates tail-recursion.  And guess what.
His Lisp solves Ackerman's function about as fast as PCC.  Strangely enough,
PCC doesn't eliminate tail recursion.  Big Deal.  I would like to learn of
those papers that perport to show that late-bound languages can be made to
compete with languages which do static binding when they can.

Finally, I should say that I consider languages like CLU, Simula, HOPE, etc
to be a major improvement on C.  Inheritance and information hiding are a
necessary part of any state-of-the-art language.  I don't think the votes
are all in on late binding yet though.