From: "Ara.T.Howard" <Ara.T.Howard@...>
Date: 2005-05-19T04:30:13+09:00
Subject: new singleton class relationship

am i the only one who finds this confusing?

   harp:~/build/ruby > cat a.rb
   class Class
     def singleton_class; class << self; self; end; end
   end
   class Parent
   end
   class Child < Parent
   end

   puts "Child < Parent #=> #{ (Child < Parent).inspect }"
   puts "Parent.ancestors #=> #{ Parent.ancestors.inspect }"
   puts "Child.ancestors #=> #{ Child.ancestors.inspect }"
   puts

   puts "Child.singleton_class < Parent.singleton_class #=> #{ (Child.singleton_class < Parent.singleton_class).inspect }"
   puts "Parent.singleton_class.ancestors #=> #{ Parent.singleton_class.ancestors.inspect }"
   puts "Child.singleton_class.ancestors #=> #{ Child.singleton_class.ancestors.inspect }"
   puts


   harp:~/build/ruby > ruby --version
   ruby 1.8.3 (2005-05-16) [i686-linux]


   harp:~/build/ruby > ruby a.rb
   Child < Parent #=> true
   Parent.ancestors #=> [Parent, Object, Kernel]
   Child.ancestors #=> [Child, Parent, Object, Kernel]

   Child.singleton_class < Parent.singleton_class #=> nil
   Parent.singleton_class.ancestors #=> [Class, Module, Object, Kernel]
   Child.singleton_class.ancestors #=> [Class, Module, Object, Kernel]


   harp:~/build/ruby > ./ruby --version
   ruby 1.9.0 (2005-05-16) [i686-linux]


   harp:~/build/ruby > ./ruby a.rb
   Child < Parent #=> true
   Parent.ancestors #=> [Parent, Object, Kernel]
   Child.ancestors #=> [Child, Parent, Object, Kernel]

   Child.singleton_class < Parent.singleton_class #=> true
   Parent.singleton_class.ancestors #=> [Class, Module, Object, Kernel]
   Child.singleton_class.ancestors #=> [Class, Module, Object, Kernel]

so - how can 'Child < Parent #=> true' when they have no ancestors in common?
note that i think it __should__ be true - but shouldn't there be at least one
common ancestor then?  it seems like Parent's singleton class should show up
in Child.singleton_class.ancestors doesn't it?

cheers.

-a
-- 
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