Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!nrl-cmf!ukma!gatech!udel!burdvax!ubbpc!wgh
From: wgh@ubbpc.UUCP (William G. Hutchison)
Newsgroups: comp.lang.smalltalk
Subject: Re: Smalltalk versus C++
Summary: I was asking about NECESSARY features, not handy
Keywords: object-oriented languages
Message-ID: <451@ubbpc.UUCP>
Date: 5 Jan 89 17:49:12 GMT
References: <447@ubbpc.UUCP> <824@laura.UUCP>
Organization: UNISYS CS, Blue Bell, PA
Lines: 55

In article <824@laura.UUCP>, georg@exunido.uucp (Georg A. M. Heeg) writes:
> In article <447@ubbpc.UUCP> wgh@ubbpc.UUCP (William G. Hutchison) writes:
> >(1) Smalltalk creates classes dynamically, whereas C++ does it statically.
> In Smalltalk you use this feature all the time. It is the way to deal with
> an interactive system to change it dynamically.

  This is interesting, but not exactly the _type_ of answer I was looking for.
It seems to me that you may be using dynamic classes because they are _there_,
not because you really need them.  Could your applications be written using
statically declared classes?  Are dynamic classes necessary for application
development in a structured "software engineering" sort of way, or just handy
for improvising programs at the terminal?
 
> >(2) In Smalltalk "everything is an object" whereas C++ treats the traditional
> >    C data types differently from programmer-defined objects;
> This feature is essentially used, too. E.g. it enables to introduce new
> kinds of Numbers (like complex) you can handle like ordinary numbers. You need
> no change of Matrix inversion algorithm after introducing Complex.

 Is this literally true?  What about checking values for "close to zero"
in pivoting?  Complex numbers are not well-ordered, so you probably want to
check if the magnitude of the number is close to zero.
 
> >(3) Smalltalk has multiple inheritance, but C++ does not yet (soon ...
> We never used this. Multiple Inheritance leads to much more complex systems
> and mostly can be avoided by distinguishing usage ("has") from inheritance 
> ("is)").

  Aha! Thanks.
 
> >(4) Smalltalk may be designed in a way such that it has built-in overhead, 
> >    and it may never be possible to make Smalltalk programs run as fast as
> >    C++ on present-day machine architectures (not sure about this ...
> This is true for small programs. Due to the good construction models and
> the good programming interface medium size programs (or large programs) often
> run blind fast in Smalltalk-80. We (Hans-Martin Mosner) wrote a vt220
> emulater in Smalltalk-80 which runs faster than most host platform window
> system terminal emulators (and has more features).
> To summarize: Flexibility and interactive visibility are the major
> differences. Both are VERY important to me.
> Georg Heeg > Smalltalk-80 Systeme > Baroper Str. 337 > D-4600 Dortmund 50


 Thanks for the info.  Does anybody know if one of the inexpensive Smalltalk
implementations runs correctly on the AT&T 6300PLUS (80286) ???

	(inews pablum)
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-- 
Bill Hutchison, DP Consultant	rutgers!liberty!burdvax!ubbpc!wgh
Unisys UNIX Portation Center
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