[Newbies] Design best practice : put state-independent methodsonclass side?

Matthew Fulmer tapplek at gmail.com
Wed Mar 26 00:02:34 UTC 2008

On Tue, Mar 25, 2008 at 07:13:27PM -0400, Rob Rothwell wrote:
>    On Tue, Mar 25, 2008 at 5:44 PM, Ramon Leon <ramon.leon at allresnet.com>
>    wrote:
>      Classes are objects too, just because most classes build instances
>      doesn't
>      mean they all have to.  You might not want a class doing both, but I see
>      no
>      reason it can't do one *or* the other.  Serving as a singleton works
>      well
>      when it's needed and keeps code simple.  Saying a class should only
>      create
>      instances seems a rather arbitrary restriction to place upon your
>      designs.
>    As a beginner who is finally starting to do some useful [Smalltalk] work
>    in a Healthcare organization, I am finding this conversation very
>    interesting because I write a lot of "utility" code...mostly data
>    "pre-processing" before it goes to the Warehouse, the Reporting engine, or
>    to files to go out the door for required reporting to other organizations.
>    Should I consider something more than just "XXFileProcessor file: aFile"
>    if it will only ever run on one file that shows up in a directory once a
>    day and the whole point is that there is only ONE processor?
>    Just interested, because in such "utility" cases I end up with all my
>    helper methods on the class side and wonder to myself, "is this wrong?"
>    because it feels very similar to writing subroutines in any other
>    language...

If it works, cool. You can always refactor later

>    On that note, isn't that sort of all traits really are?  A subroutine not
>    attached to any particular object?   But with no access to object data
>    short of resorting to things like self classPool at: #Var, which I suppose
>    defeats the point, but darn it, I keep running into situations where
>    multiple inheritence would be great! 
>    Rob Rothwell

No. Traits are units of behavior that can be shared among

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Matthew Fulmer -- http://mtfulmer.wordpress.com/

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