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From: craig@elaine35.Stanford.EDU (Craig Chambers)
Newsgroups: comp.object,comp.lang.ada
Subject: Re: ada-c++ productivity
Message-ID: <1991Mar16.000624.2513@leland.Stanford.EDU>
Date: 16 Mar 91 00:06:24 GMT
References: <11966@pasteur.Berkeley.EDU> <EACHUS.91Mar14190050@aries.mitre.org> <1991Mar15.224626.27077@aero.org>
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In article <1991Mar15.224626.27077@aero.org> jordan@aero.org (Larry M. Jordan) writes:
>Language	Inheritance	DynamicBnd'g	Type[T]	Except.	Task 	LibMgr
>C++		yes-MI/class	yes-vft		no[1]	no[2]	no	hand
>Objective-C	yes-SI/class	yes-tlu		no	no	no	hand
>Smalltalk	yes-SI/class	yes-tlu		no	no	no	?
>SELF		yes-MI/object	yes-?		no	no	no	?
>TP6.0		yes-SI/class	yes-vft		no	no	no	auto
>Eiffel		yes-MI/class	yes-vft		yes	yes	no	auto
>Ada		yes[3]		no		no[4]	yes	yes	auto

I'd argue that the mechanism for implementing dynamic binding is not
so important, certainlyt not as important as many of the other
features you list.  But if you want to include it, Self's
implementation of dynamic binding is based on hash table lookup with
possible optimizations like in-line caching (also present in the
ParcPlace Smalltalk-80 implementation), static binding, and inlining.
I'd also guess that Eiffel uses tlu instead of vft to implement
dynamic binding.

Both Smalltalk and Self support multiple lightweight communicating
threads within a single address space, so those values should probably
read "yes" (depending on what you mean by "Task").

Also, both Smalltalk and Self implementations are effectively one big
library manager.  If you require some sort of separate compilation,
then they don't have it, but if you just want automatic linking and
compilation after programming changes or the ability to invoke code of
objects/classes written by other people, then they are nice
environments.

-- Craig Chambers

P.S.  The eariler mention of "Cardelli and Wegner's" definition of OO
should be attributed to just Wegner.  Wegner's definitions are overly
narrow and constrained in my view, and I believe that Cardelli would
want to be able to form his own definitions.