RedBlog

This is my first blog-post using a chiny new off-line blogging software! Anyway, this post will be about Python and one of its ugglier corners.

You probably know that calling the implementation of a method in a superclass is easy. But what about a class-method?

Lets give it a try:

>>> class X(object):
...  @classmethod
...  def foo(cls):
...   return cls.__name__
... 
>>> class Y(X):
...  @classmethod
...  def foo(cls):
...   return "NANA: " + X.foo()
... 
>>> Y.foo()
'NANA: X'

Nah, didn't work, and we couldn't expect it too - we didn't send X.foo any cls parameter. But how could we send it? X.foo does not take a parameter, it is given X implicitly as a first argument. It doesn't work as with ordinary methods...

Note that it is possible to get the "right" result if we didn't override foo:

>>> class Z(X):
... 
>>> Z.foo()
'Z'

The only solution I came up with (that doesn't involve super()) is this uggly one:

>>> class X(object):
...  @classmethod
...  def foo(cls):
...   return cls.__name__
... 
>>> class Y(X):
...  @classmethod
...  def foo(cls):
...   return "NANA: " + X.foo.im_func(cls)
... 
>>> Y.foo()
'NANA: Y'