From: KONTRA Gergely <kgergely@...>
Date: 2003-04-14T22:19:12+09:00
Subject: [Q] A class, that knows about it's instances + Sets

Hi!

In my recent project, I need, that a class knows about their instances.

So after
class MyClass
...
end
a,b=MyClass.new,Myclass.new

I except MyClass.instances to give me an array [a,b]
Or I would be happy, if I can do
MyClass.each{|a| ... }

I can do it in one class, BUT, I need it as a module, because I cannot
subclass my class from that class?

BTW Is the latter solution "cheaper" (memory, execution time...)

And, another question, which is more general:
Has ruby a set type?
Implementing them with an array is not appropiate, because lookup is
slow in an array. And, I'm confused about the set methods in the array
classes. When I need sets, I always use hashes with dummy values, but I
think a separate class would be nice.

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