General talk about software patterns

[Jesús Alonso <kenchoweb AT hotmail.com>]

Hello Holger,

In my opinion, it simply depends on how familiar you are with the pattern 
you are to recognise. Patterns like Façade, Observer, or Singleton are quite 
easy to find, and some patterns are more a philosophy than a generic 
structure, like the Façade or the Template Method, what makes them easy to 
find in code. Of course, if you have the design diagrams and not just the 
source code, they are much easier to spot.

Also, a few days ago Jens Dietrich sent a mail to one of these lists to 
announce their research project regarding automated pattern recognition in 
source code. The link is: http://www-ist.massey.ac.nz/wop/

About editting code, design patterns usually give the most appropiate 
solution for a problem. This solution stablishes a good design philosophy 
everyone should follow as much as possible. So the programmer just should 
have to follow that same OOP philosophy when editting that code. Based on a 
well defined structure and following correct OOP usually leads to the 
correct solution, even if he doesn't recognise the pattern or even doesn't 
know anything about it. From my personal experience, extending existing 
patterns-dense code was easy and found myself implementing the Observer 
pattern before I ever heard of it. Just as an example, anyone who has 
programmed a GUI in Java has found himself applying the Observer pattern 
everytime they create a new Listener (Observer participant) and attach them 
to a graphical component (attach method in Subject participant). As you can 
see, a well trained programmer will hardly destroy patterns when editting 
patterns-dense code.

Hope that helps.

Best regards,
 Jesús Alonso


> Hi Mike,
>
> Mike Beedle wrote:
> > Any more “positive feedback” out there?
>
> YES. Thanks very much for your posting.
>
> I always appreciate hints towards a more general view on structures than 
> just "technical" views from a software engineer's view (or even a Java 
> programmer's).
>
> I also have a question and request:
>
> You say pattern usage is at least partly a cognitive process. Typically 
> cognitive processes can be error-prone (misinterpretation of structures, 
> obfuscation, easy and difficult to recognize structures, ...). In 
> particular when it comes to formal stuff like a program.
>
> Does anybody has links or own experience about problems with software 
> patterns on this level? E.g. how good are they recognized in code? Under 
> what circumstances is an average programmer able to edit pattern-dense code 
> correctly, or when does he eventually destroy patterns by chance?
>
> Thanks for
>
> --
> Holger Muegge
>
> University of Bonn, Institute of Computer Science III
> Roemerstrasse 164,  D-53117 Bonn, Germany
> Phone/Fax:          +49-228-73-6528 / -4382
>
>
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