gistfile1.rb

# http://rubinius.lighthouseapp.com/projects/5089/tickets/614-calling-a-class-method-on-an-object-s-metaclass-should-invoke-the-class-method-of-the-object-s-class#ticket-614-5

class Object
  # The hidden singleton lurks behind everyone
  def metaclass; class << self; self; end; end
  def meta_eval(&blk)
    metaclass.instance_eval(&blk)
  end

  # Adds methods to a metaclass
  def meta_def name, &blk
    meta_eval { define_method name, &blk }
  end
end

class B
end

b = B.new

# false in Rubinius, true in MRI, JRuby
p b.metaclass.superclass.object_id == B.metaclass.object_id

b.meta_def(:cheese) {'cheshire'}

# false in all implementation
p b.metaclass.superclass.object_id == B.metaclass.object_id