Python pattern for defaulting to a 'grandparent' class's implementation

问题

class Thing(object):
  def sound(self):
    return '' #Silent

class Animal(Thing):
  def sound(self):
    return 'Roar!'

class MuteAnimal(Animal):
   def sound(self):
    return '' #Silent

Is there a pattern in python for MuteAnimal's sound to refer to its grandparent class Thing's implementation? (eg super(MuteAnimal,self).super(Animal.self).sound() ?) Or is Mixin a better use case here?

回答1:

As said by Alexander Rossa in Python inheritance - how to call grandparent method? :

There are two ways to go around this:

Either you can use explicitly A.foo(self) method as the others have suggested - use this when you want to call the method of the A class with disregard as to whether A is B's parent class or not:

class C(B):   def foo(self):
    tmp = A.foo(self) # call A's foo and store the result to tmp

return "C"+tmp 

Or, if you want to use the .foo() method of B's parent class regardless whether the parent class is A or not, then use:

class C(B):   def foo(self):
    tmp = super(B, self).foo() # call B's father's foo and store the result to tmp
    return "C"+tmp

回答2:

Is it sensible to do this?

In MuteAnimal.sound, call super(Animal, self).sound()

because Animal is in fact, gradparent class of MuteAnimal...

来源：https://stackoverflow.com/questions/42937114/python-pattern-for-defaulting-to-a-grandparent-classs-implementation