On 17 December 2010 02:07, Andreas Raab <andreas.raab at gmx.de> wrote:
> On 12/16/2010 2:10 PM, Igor Stasenko wrote:
>>
>> 2010/12/16 Janko Mivšek<janko.mivsek at eranova.si>:
>>>
>>> Guys, for Thursday funny: "It is really goofy that some people do not
>>> understand the price-value relationship of classes in object-oriented
>>> systems." http://twitter.com/#!/renggli
>>>
>>> Well, I couldn't resist :)
>>
>> Me too.. me too.
>> It would be good to hear arguments from other side here.
>
> Indeed. From my perspective there are some pretty straightforward rules for
> when creating additional classes is a good idea.
>
> For example, I am a big fan of Announcements, since they make the set of
> events that are part of an application explicit. Even though one can just
> use names (i.e., self signalEvent: #foo) having each event be a separate
> class is beneficial because a user who doesn't know what events exist, can
> find those, can find out where they are signaled, and how they are used.
>
> Or Exceptions. Another good use for having additional classes. Both for
> purposes of documentation (what exceptions exist) as well as for extending
> them. For example, I can add a subclass of ConnectionError in my application
> and generic handlers for ConnectionError in third party code will be able to
> catch the error correctly.
>
> Or the command pattern itself, which is extremely useful in many situations,
> like when you need to reason about bulk sets of method invocations (in undo
> for example).
>
> So there are indeed various reasons for when adding additional classes can
> be very, very beneficial. But let's not forget that there's a cost
> associated with it as well. If it were different, if there was really no
> cost associated with having a class, how about we make all of the 2000 Morph
> methods into commands? If there is no cost to it, then it must be
> beneficial, right?
>
> So yes, I understand that there's a cost-benefit ratio for adding additional
> classes. But if there's a good reason for these classes in Gofer, then I
> just don't see it. None of the rules for when additional classes are a good
> idea seem to apply. In which case Occam's razor wins.
>
> Now if I only could make that argument in 140 characters... but then no
> sensible argument has ever been made on Twitter and none ever will, so who
> cares.
>

Those who wants to learn and exchange their experience, like me want to see
different argumentation with pro and cons, so we can make some
conclusions and learn something new.

My own ruleset is simple:
It is not necessary to always follow same rules, except two: DRY and KISS.

> Cheers,
>  - Andreas
>
>



-- 
Best regards,
Igor Stasenko AKA sig.