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From: tma@osc.COM (Tim Atkins)
Newsgroups: comp.object,comp.lang.objective-c
Subject: Re: Do we really need types in OOPL's?
Message-ID: <3957@osc.COM>
Date: 1 Nov 90 20:33:50 GMT
References: <1426@media01.UUCP> <1990Oct9.190813.23402@ux1.cso.uiuc.edu> <2444@runxtsa.runx.oz.au> <1990Oct19.180646.8649@ux1.cso.uiuc.edu>
Reply-To: tma@osc.UUCP (Tim Atkins)
Followup-To: comp.object
Organization: Versant Object Technology, Menlo Park, CA
Lines: 16

As far as method lookup speed advantages possible with strong typing
some work I did in Objective C a couple of years ago may be of some
interest.  I attempted several improvments of the standard algorithm
and finally achieved a general lookup in the absence of strong typing
on the order of 15 assembler instructions on a Sun 3.  Adding type hints
(not strong typing but just a hint of the expected type of referenced
objects) and using code of the form:

	implementation = (runtime_type == expected_type) ? precomputed_imp :
		full_lookup(...);

cut the average lookup costs in half for the applications I instrumented.
Therefore, it seems to me that not strong typing, but weak type hints are
worthwhile for gaining improvements in this area.

- Tim Atkins