[PWS] Only one PWS instance possible?

Mark Guzdial guzdial at cc.gatech.edu
Fri May 7 14:06:59 UTC 1999


>According to Ralph Johnson, this is a shanda (translation: really
>groty and losing thing).  Using classes as a vehicle to enforce
>singleton's is one thing, but the difficulty with that approach is
>precisely that it invites problems when reusers desire to produce
>multiples instances in the distant future.
....
>While there is an appealing compactness of putting PWS and its
>request instances together, that compactness really doesn't buy
>anything, and invites confusion later.  As a stylistic matter (from
>one barely an adolescent in Smalltalk coding), Professor Johnson's
>remarks seemed salient.


*COMPLETELY* agreed!  There is a certain authenticity to my class lectures
when I can say, "Look -- I've made these mistakes too.  Right here's a big
one!!"

As Bolot says, it's one of the top-level goals of PWS to get rid of this
reliance on class-side behavior.

My apologies -- I'm still a learning Squeak hacker, too!
  Mark

--------------------------
Mark Guzdial : Georgia Tech : College of Computing : Atlanta, GA 30332-0280
(404) 894-5618 : Fax (404) 894-0673 : guzdial at cc.gatech.edu
http://www.cc.gatech.edu/gvu/people/Faculty/Mark.Guzdial.html





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