## mark a section (Learn more)

#http://whytheluckystiff.net/articles/seeingMetaclassesClearly.html 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 # Defines an instance method within a class def class_def name, &blk class_eval { define_method name, &blk } end end class A def cheese 'shropshire blue' end def self.cheese 'edam' end end class B < A def cheese 'cheddar' end def self.cheese 'stilton' end end a = A.new b = B.new b_with_meta = B.new b_with_meta.meta_def(:cheese) {'cheshire'} b_with_meta_meta = B.new b_with_meta_meta.meta_def(:cheese) {'brie'} b_with_meta_meta.metaclass.meta_def(:cheese) {'gouda'} b_with_meta_meta.metaclass.metaclass.meta_def(:cheese) {'wensleydale'} puts "A.cheese: #{A.cheese}" puts "B.cheese: #{B.cheese}" puts "a.cheese: #{a.cheese}" puts "b.cheese: #{b.cheese}" puts "b_with_meta.cheese: #{b_with_meta.cheese}" puts "b_with_meta.metaclass.cheese: #{b_with_meta.metaclass.cheese}" puts "b_with_meta_meta.cheese: #{b_with_meta_meta.cheese}" puts "b_with_meta_meta.metaclass.cheese: #{b_with_meta_meta.metaclass.cheese}" puts "b_with_meta_meta.metaclass.metaclass.cheese: #{b_with_meta_meta.metaclass.metaclass.cheese}"

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