Python：调用parent instancemethod

Question

For example, I have next code:

class Dog:
    def bark(self):
        print "WOOF"

class BobyDog( Dog ):
    def bark( self ):
        print "WoOoOoF!!"

otherDog= Dog()
otherDog.bark() # WOOF

boby = BobyDog()
boby.bark() # WoOoOoF!!

BobyDog is a child of Dog and have overrided instancemethod "bark".

How I can refer to parent method "bark" from instance of class "BobyDog"?

In other words:

class BobyDog( Dog ):
    def bark( self ):
        super.bark() # doesn't work
        print "WoOoOoF!!"

otherDog= Dog()
otherDog.bark() # WOOF

boby = BobyDog()
boby.bark()
# WOOF
# WoOoOoF!!

Answer 1

You need to call the super() function, and pass in the current class ( BobyDog ) and self :

class BobyDog( Dog ):
    def bark( self ):
        super(BobyDog, self).bark()
        print "WoOoOoF!!"

More importantly, you need to base Dog on object to make it a new-style class; super() does not work with old-style classes:

class Dog(object):
    def bark(self):
        print "WOOF"

With these changes the call works:

>>> class Dog(object):
...     def bark(self):
...         print "WOOF"
... 
>>> class BobyDog( Dog ):
...     def bark( self ):
...         super(BobyDog, self).bark()
...         print "WoOoOoF!!"
... 
>>> BobyDog().bark()
WOOF
WoOoOoF!!

In Python 3, old-style classes have been removed; everything is new-style, and you can omit the class and self parameters from super() .

In old-style classes, the only way to call the original method is by referring directly to the unbound method on the parent class and manually pass in self :

class BobyDog( Dog ):
    def bark( self ):
        BobyDog.bark(self)
        print "WoOoOoF!!"