Ruby：如何获取在子类中重新定义的父方法

Question

如何在下面的代码中从Up类获取Base的“hello”方法？

class Base
  def hello
    p 'hello from Base'
  end
end

class Up < Base
  def hello_orig
    # how to call hello from Base class?
  end

  def hello
    p 'hello from Up'
  end
end

u = Up.new
u.hello_orig # should return 'hello from Base' 

Answer 1

您也可以使用别名。

class Base
  def hello
    p 'hello from Base'
  end
end

class Up < Base
  alias hello_orig hello

  def hello
    p 'hello from Up'
  end
end

u = Up.new
u.hello_orig # should return 'hello from Base' 

Answer 2

试试这个，

class Base
  def hello
    p 'hello from Base'
  end

end

class Up < Base
  def hello_orig
    Base.instance_method(:hello).bind(self).call

  end

  def hello
    super() 
    p 'hello from Up'
  end

end

u = Up.new
u.hello_orig # should return 'hello from Base' or
u.hello