Why can't I subclass datetime.date?

Question

Why doesn\'t the following work (Python 2.5.2)?

>>> import datetime
>>> class D(datetime.date):
        def __init__(self, year):
                  


        

Answer 1

You can wrap it and add extended functionality to your wrapper.

Here is an example:

class D2(object):
    def __init__(self, *args, **kwargs):
        self.date_object = datetime.date(*args, **kwargs)

    def __getattr__(self, name):
        return getattr(self.date_object, name)

And here is how it works:

>>> d = D2(2005, 10, 20)
>>> d.weekday()
3
>>> dir(d)
['__class__', '__delattr__', '__dict__', '__doc__', '__getattr__',
 '__getattribute__', '__hash__', '__init__', '__module__', '__new__',
 '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__str__',
 '__weakref__', 'date_object']
>>> d.strftime('%d.%m.%Y')
'20.10.2005'
>>>

Note that dir() doesn't list datetime.dates attributes.