class AccTest
  def pub
    puts "pub is a public method."
  end
  public :pub       # pubメソッドをpublicに設定（指定しなくてもよい）
  def priv
    puts "priv is a private method."
  end
  private :priv     # privメソッドをprivateに設定
end

acc = AccTest.new
acc.pub             #=> pub is a public method.
acc.priv            #=> エラー