メソッド入れ替えマン

replace_method.rb

class Nyan
  def replace_method(a, b)
    (class << self; self end).module_exec do
      alias_method "#{a}_backup", a
      alias_method a, b
      alias_method b, "#{a}_backup"
    end
  end

  def method1
    :method1
  end

  def method2
    :method2
  end
end

nyan = Nyan.new

p [nyan.method1, nyan.method2] #=> [:method1, :method2]

nyan.replace_method :method1, :method2

p [nyan.method1, nyan.method2] #=> [:method2, :method1]

nyan.replace_method :method1, :method2

p [nyan.method1, nyan.method2] #=> [:method1, :method2]