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From: lsr@apple.UUCP
Newsgroups: comp.lang.misc
Subject: Re: Dynamic Binding and Dynamic Type Checking
Message-ID: <412@apple.UUCP>
Date: Tue, 27-Jan-87 14:30:17 EST
Article-I.D.: apple.412
Posted: Tue Jan 27 14:30:17 1987
Date-Received: Wed, 28-Jan-87 23:19:17 EST
References: <4000001@nucsrl.UUCP> <3288@milano.UUCP> <147@m10ux.UUCP> <672@unc.unc.UUCP> <6565@alice.uUCp> <459@watcgl.UUCP>
Reply-To: lsr@apple.UUCP (Larry Rosenstein)
Organization: Advanced Technology Group, Apple Computer
Lines: 35

In article <459@watcgl.UUCP> kdmoen@watcgl.UUCP (Doug Moen) writes:
>I agree that dynamic type checking is a problem.  I had an opportunity
>to play with Alan Bornings "ThingLab" and Randy Smiths "Alternate Reality Kit".
>These are both large applications written in Smalltalk.
>I was able to cause both programs to seize up with "message not understood"
>errors just by playing around.  Although Smalltalk is great for rapid
>prototyping, it isn't suitable for programming large, *robust* applications,
>because you can never be sure that you haven't found all the type errors.
>

I am not sure if this is valid.  Aren't Thinglab and ARK just research
projects and not finished applications?  There are a few commercial
applicatiosn written in Smalltalk (e.g., the Humble expert system from
Xerox).  It would be more meaningful to look at one of these and see how
reliable it is.

>However, there is no reason why a language could not support static
>type checking and dynamic binding.

Agreed.  Object Pascal does this.  You still have to do sufficient testing
on your program; I don't think object-oriented programs are any worse in
this respect.

Also, in Smalltalk you can implement messageNotUnderstood and try to correct
the problem.

-- 
Larry Rosenstein

Object Specialist
Apple Computer

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