Hello Lothar


Lothar Schenk wrote:

> Am Montag, 15. Dezember 2003 13:16 schrieb Nathanael Schärli:
> 
> 
>>In fact, there were dozens of places deep in the core of the system
>>(e.g., in the Morphic framework) that caused a runtime error just
>>because I was being a good programmer and actually declared abstract
>>methods as 'subclassResponsibility', which is unarguably a good style of
>>programming.
> 
> 
> Whenever I hear someone say that something is "unarguably" so, it raises the 
> itch in me to argue. :)



Question:
> Why is it 'unarguably' good style to fill abstract methods with the line "self 
> subclassResponsibility"? 


Answer:
Because this is an idiomatic convention in the Smalltaker subculture to 
define a method as abstract; see Kent Becks book about Smalltalk idioms.


The point ot Nathanael is that he likes the system to have a way of 
distinguishing between abstract and non-abstract methods. That's what he 
means when he writes the following

<citation Nathanael>
And even though this may seem like a simple and good solution at a first
 > glance, it introduces a lot of problems because this way of declaring
 > abstract methods is not understood by the meta-protocol of the Smalltalk
 > language. As a consequence, all the meta-functionality of Smalltalk
 > (i.e., methods such as #canUnderstand: and #respondsTo:) thinks that
 > such abstract or disabled methods are regular methods that are
 > intended/expected to be called.
</citation Nathanael>


Even if Smalltalk is a relatively good language it does not mean that it 
is the only one and that it couldn't be cleaned up or enhanced somewhat.

Between 1970 and 1980 every two years a new version of Smalltalk was 
developed. Now we have 2003. Why not have a little clean-up?

In general OO software engineering circle the distinction between 
abstract and non-abstract methods is considered to be a valuable 
distinction. Lothar, I really do not see your point.



Cheers
Hannes