From: "Jesús Gabriel y Galán" <jgabrielygalan@...>
Date: 2011-08-02T15:54:39+09:00
Subject: Re: system stack error in ObjectSpace.each_object

On Tue, Aug 2, 2011 at 3:12 AM, luke gruber <luke.gru@gmail.com> wrote:
> 1) For the container idea, how would you go about doing this?

In the initialize (or new) method of Foo, store self in a container
(an array on Foo, or another class).
But take into account that this means that all instances of Foo will
have an alive reference, so they will never be garbage collected.
Something like:

ruby-1.8.7-p334 :003 > class FooCollection
ruby-1.8.7-p334 :004?>   class << self
ruby-1.8.7-p334 :005?>     attr_reader :collection
ruby-1.8.7-p334 :006?>     def << item
ruby-1.8.7-p334 :007?>       (@collection ||= []) << item
ruby-1.8.7-p334 :008?>       end
ruby-1.8.7-p334 :009?>     end
ruby-1.8.7-p334 :010?>   end
 => nil
ruby-1.8.7-p334 :015 > class Foo
ruby-1.8.7-p334 :016?>   def initialize
ruby-1.8.7-p334 :017?>     FooCollection << self
ruby-1.8.7-p334 :018?>     end
ruby-1.8.7-p334 :019?>   end
 => nil
ruby-1.8.7-p334 :020 > a = Foo.new
 => #<Foo:0xb70d9c80>
ruby-1.8.7-p334 :021 > b = Foo.new
 => #<Foo:0xb70d7dcc>
ruby-1.8.7-p334 :022 > FooCollection
 => FooCollection
ruby-1.8.7-p334 :023 > FooCollection.collection
 => [#<Foo:0xb70d9c80>, #<Foo:0xb70d7dcc>]

Take note that even if a and b go out of scope, the Foo instances they
referenced will never be GCed, because they are referenced by the
FooCollection.collection array.

Jesus.