Newsgroups: comp.lang.smalltalk
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From: dbuck@superior.carleton.ca (Dave Buck)
Subject: Re: self subclassResposibility
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References: <Pine.HPP.3.91.951124180816.6655A-100000@hp17.zdv.uni-tuebingen.de>
Date: Fri, 24 Nov 1995 19:44:15 GMT
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In article <Pine.HPP.3.91.951124180816.6655A-100000@hp17.zdv.uni-tuebingen.de>,
Gerrit Jackson  <zxmme12@hp17.zdv.uni-tuebingen.de> wrote:
>Dull question: what does subclassResposibility exactly mean, and what 
>does one use it for ?

The subclassResponsibilty method just produces an error message.  It's
meant to be used in abstract methods to write methods which are
necessary for the subclasses to implement but can't be implemented at
the superclass level.  The purpose of having these methods at all is:

   1) They document the public interface indicating that this method
exists and is callable in all subclasses.

   2) Serves as documentation to the implementers of subclasses that
this method must be implemented.

   3) Produces a runtime error in case the subclasses didn't redefine
this method.

In a properly working system, this method would never be called.

>As I could not find any Smalltalk implementation for Amigas (except for one 
>that seemed to crash the system for almost nonexistent reasons), I am 
>currently trying to build a smaller Smalltalk myself (I call it TinyTalk 
>to make the difference clear).

Timothy Budd has a version of Smalltalk called Tiny Smalltalk.  If you
plan to release your version in any way, the name may be confused.

Writing your own Smalltalk can be a daunting task especially if you
haven't seen a real Smalltalk implementation.  Do you have a handle on
how to do message passing, garbage collection, bytecodes, primitives,
etc?  If you have any specific questions, EMail me and I'll see if I
can help out.  I think that level of detail is beyond the scope of
comp.lang.smalltalk.


David Buck
dbuck@ccs.carleton.ca

_________________________________
| David K. Buck                 |
| dbuck@ccs.carleton.ca         |
| The Object People             |
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