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From: wg@opal.cs.tu-berlin.de (Wolfgang Grieskamp)
Newsgroups: comp.object,comp.lang.misc
Subject: Re: A Hard Problem for Static Type Systems
Message-ID: <3156@opal.cs.tu-berlin.de>
Date: 25 Apr 91 00:56:36 GMT
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gudeman@cs.arizona.edu (David Gudeman) writes:

>In article  <51669@nigel.ee.udel.edu> Darren New writes:
>]... Hermies has dynamic typing (via polymorph) without dynamic
>]binding (in the normal OO sense).  C++ has some limited dynamic binding
>]without dynamic typing.  Smalltalk intermixes the dynamic typing and
>]the dynamic binding semantically, muddying the waters.

>OK, I give up.  What is the difference between dynamic typing and
>dynamic binding?

I guess the following:

C++ is "strongly typed" with dynamic binding (according to "virtuals"), 
since the error "message not understood" is not part of the languages 
operational semantics. Each message send to an object will be understood 
by one of its classes in the class hierarchy (however, the final 
superclass may implement the message by printing "message not 
understood" and just exit()...). 

Smalltalk is "dynamically typed" with dynamic binding, since the error
"message not understood" is part of the languages operational semantics.

--
Wolfgang Grieskamp 
wg@opal.cs.tu-berlin.de tub!tubopal!wg wg%opal@DB0TUI11.BITNET