Python 2: someIterator.next() vs. next(someIterator) :Python 3

Question

In Python 2 iterators offer .next(), a callable method:

it = iter(xrange(10))
it.next()
> 0
it.next()
> 1
...

In Python

Answer 1

You are directly asking about PEP 3114

consider the following code:

class test:
    def __iter__(self):
        return self
    def next(self):
        return "next"
    def __next__(self):
        return "__next__"

x = test()
for i,thing in enumerate(x):
    print(thing)
    if i>4:
        break

in python 2 next is printed but in python 3 __next__ is printed, since the method is being called implicitly it makes way more sense to match other implicit methods such as __add__ or __getitem__, which is described in the PEP.

If you are planning on using next explicitly then much like len, iter, getattr, hash etc. then python provides a built in function to call the implicit function for you. At least... after PEP 3114.