__getattr__ on a class and not (or as well as) an instance

Question

I know I can write code like:

class A :
    def __getattr__ (self, name) :
        return name

to trap access to undefined attributes on an

Answer 1

Yes you can. Metaclasses are the answer.

class MyMetaclass(type):
    def __getattr__(cls, name):
        return "cls.%s" % name


class A :
    __metaclass__ = MyMetaclass
    def __getattr__ (self, name) :
        return name

print A().ATTR
print A.ATTR

will output

ATTR
cls.ATTR

Answer 2

You can use a metaclass:

In [1]: class meta(type):
   ...:     def __getattr__(self, name):
   ...:         return name
   ...:     
   ...:     

In [2]: class A(object):
   ...:     __metaclass__ = meta
   ...:     def __getattr__(self, name):
   ...:         return name
   ...:     
   ...:     

In [3]: A().attr
Out[3]: 'attr'

In [4]: A.attr
Out[4]: 'attr'