Sridhar Ratnakumar Sridhar Ratnakumar - 1 month ago 9
Python Question

Calling a base class's classmethod in Python

Consider the following code:

class Base(object):

@classmethod
def do(cls, a):
print cls, a

class Derived(Base):

@classmethod
def do(cls, a):
print 'In derived!'
# Base.do(cls, a) -- can't pass `cls`
Base.do(a)

if __name__ == '__main__':
d = Derived()
d.do('hello')

> $ python play.py
> In derived!
> <class '__main__.Base'> msg


From
Derived.do
, how do I call
Base.do
?

I would normally use
super
or even the base class name directly if this is a normal object method, but apparently I can't find a way to call the classmethod in the base class.

In the above example,
Base.do(a)
prints
Base
class instead of
Derived
class.

Answer
super(Derived, cls).do(a)

EDIT: Oh, wait a minute... it's not clear exactly what you're asking. This is how you would invoke the code in the base class's version of the method, from the derived class.