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From: mikeb@ee.ubc.ca (Mike Bolotski)
Newsgroups: comp.lang.misc
Subject: Re: Languages that allow extensions to classes
Message-ID: <1240@fs1.ee.ubc.ca>
Date: 12 Apr 90 17:57:47 GMT
References: <16560@estelle.udel.EDU> <1238@fs1.ee.ubc.ca> <22413@cs.yale.edu>
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Organization: Dept of EE, University of British Columbia
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In article <22413@cs.yale.edu>, briscoe-duke@CS.YALE.EDU (Duke Briscoe) writes:
|> Don't some CLOS systems have a browser which allows you to look at
|> (and edit) the source for a class' methods regardless of what file was
|> loaded to define the method?  I'm not a big fan of depending on plain
|> text files as a way of representing programs; richer data structures
|> (like what a browser uses) would be preferable, which are offered to
|> some extent by Smalltalk and some Lisp environments.

Such a browser would be quite welcome but neither the Apollo nor Sun
CL systems that I use include it.   In any case, the browser is a
reflection of the *environment*, not of the *language* itself.   
C++ enforces certain software engineering principles that
CLOS doesn't.  Whether those principles are a good idea is a different
argument

But this shouldn't really be surprising, seeing as CLOS allows you to
dig out any instance variable/slot no matter  how hard you try to hide
it.  A reflection of the CL philosophy of bypassing the package
mechanism by the simple expedient of using :: instead of :  .

|> I think the other issue is whether a language has the capability of
|> incrementally extending or redefining definitions without having to
do |> massive recompilation.  This often involves an extra level of |>
indirection which has a performance price, but the performance price |>
can be "unpaid" by having a "final version" compiler which eliminates
|> the indirection, since that feature is mainly needed only during

Very very interesting idea.

Mike Bolotski, Department of Electrical Engineering,
               University of British Columbia, Vancouver, Canada 
mikeb@salmon.ee.ubc.ca             | mikeb%salmon.ee.ubc.ca@relay.ubc.ca