Is there any case where len(someObj) does not call someObj's __len__ function?

Question

Is there any case where len(someObj) does not call someObj\'s __len__ function?

I recently replaced the former with the latter in a (sucess

Answer 1

I think the answer is that it will always work -- according to the Python docs:

__len__(self):

Called to implement the built-in function len(). Should return the length of the object, an integer >= 0. Also, an object that doesn't define a __nonzero__() method and whose __len__() method returns zero is considered to be false in a Boolean context.