Ruby Fu

fu.rb

class Foo
  def t
    puts "Foo"
  end
end

module T
  def t
    puts "T"
    super
  end
end

module TT

end

class Bar < Foo
  include T
  include TT

  TT.instance_eval do
    define_method :t do
      puts "TT"
      super
    end
  end

  def t
    puts "Bar"
    super
  end
end

Bar.new.t
puts '-'*15

Bar.class_eval do
  def foo
    puts 'class'
  end
end

Bar.instance_eval do
  def foo
    puts 'instance'
  end
end

Bar.new.foo
Bar.foo