broken-hook.rb

=begin

Class Hierarchy

     A
    / \
   B1 B2
  /     \
 C1     C2

=end


class A
  def self.inherited(sub)
    puts "A has new descendant #{sub}"
  end
end

class B1 < A
end

class C1 < B1
end

class B2 < A
  def self.inherited(sub)
    puts "B2 has new descendant #{sub}"
  end
end

class C2 < B2
end


 
# actual output:
=begin
A has new descendant B1
A has new descendant C1
A has new descendant B2
B2 has new descendant C2
=end


# well designed OO language output:
=begin
A has new descendant B1
A has new descendant C1
A has new descendant B2
B2 has new descendant C2
A has new descendant C2             <- !
=end


=begin

'A' needs self.inherited to work, regardless of what it's subtypes
decide to put class methods on. This is one gist where I think the ruby
object system is silly. 

=end