[Tutor] __iter__

[Danny Yoo]

> Where/how/when is 'def next(self(:' called?

The 'for' loop statement does this internally when it marches across an
iterable thing.  We can write something something like this:

######################
for item in thing:
    print item
######################


Python is doing something like this behind the scenes:

######################
iterable = iter(thing)
try:
    while True:
        item = iterable.next()
        print item
except StopIteration:
    pass
######################



The for loop is the one that's calling next() repeatedly on its iterable.
We can manually call next() ourselves, just to see what happens:

######
>>> names = ['homer', 'marge', 'sideshow bob']
>>> iterable = iter(names)
>>> iterable
<listiterator object at 0x6fdf0>
>>>
>>>
>>> iterable.next()
'homer'
>>> iterable.next()
'marge'
>>> iterable.next()
'sideshow bob'
>>> iterable.next()
Traceback (most recent call last):
  File "<stdin>", line 1, in ?
StopIteration
######

Does this make sense?