如何調用super.super方法在Ruby中

Question

我有以下類

class Animal 
    def move 
    "I can move" 
    end 
end 

class Bird < Animal 
    def move 
    super + " by flying" 
    end 
end 

class Penguin < Bird 
    def move 
    #How can I call Animal move here 
    "I can move"+ ' by swimming' 
    end 
end 

我怎麼能說裏面企鵝動物的舉動方法？我不能使用super.super.move。有什麼選擇？

感謝

Answer 1

你可以得到的Animal的move實例方法，將其綁定到self，然後調用它：

class Penguin < Bird 
    def move 
    m = Animal.instance_method(:move).bind(self) 
    m.call 
    end 
end 

Answer 2

class Penguin < Bird 
    def move 
    grandparent = self.class.superclass.superclass 
    meth = grandparent.instance_method(:move) 
    meth.bind(self).call + " by swimming" 
    end 
end 

puts Penguin.new.move 

有關此方法的詳細信息，閱讀this answer

Answer 3

你可以這樣做（我建議here）：

class Penguin < Bird 
    def move 
    puts self.class.ancestors[2].instance_method(__method__).bind(self).call + 
    ' by swimming' 
    end 
end 

Penguin.new.move 
    # I can move by swimming 

[編輯：我看到這與@ August的答案很相似。這具有輕微的優勢，即Animal和move都不是硬連線。]

Answer 4

如果您使用的是Ruby 2.2.0，那麼您的盤中就有新的東西。那東西是：Method#super_method。

class Animal 
    def move 
    "I can move" 
    end 
end 

class Bird < Animal 
    def move 
    super + " by flying" 
    end 
end 

class Penguin < Bird 
    def move 
    method(__method__).super_method.super_method.call + ' by swimming' 
    end 
end 

Penguin.new.move # => "I can move by swimming" 

我完全同意Robert Klemme's和他的答案是最好的，乾淨。