Am 08.12.2015 um 02:05 schrieb Robert:
Hi,
When I learn for loop with below link:
http://www.shutupandship.com/2012/01/understanding-python-iterables-and.html
it has such explanation:
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for loop under the hood
First let's look at the for loop under the hood. When Python executes the
for loop, it first invokes the __iter__() method of the container to get the
iterator of the container. It then repeatedly calls the next() method
(__next__() method in Python 3.x) of the iterator until the iterator raises a
StopIteration exception. Once the exception is raised, the for loop ends.
\\\\\\\\\
When I follow a list example from the above link, and one example of myself:
//////////
xx=[1,2,3,4,5]
xx.next
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
<ipython-input-76-dd0716c641b1> in <module>()
----> 1 xx.next
AttributeError: 'list' object has no attribute 'next'
xx.__iter__
Out[77]: <method-wrapper '__iter__' of list object at 0x000000000A1ACE08>
for c in xx: print c
1
2
3
4
5
//////////////
I am puzzled that the list examples have no next method, but it can run as
a for loop. Could you explain it to me the difference?
Lists don't have a next method. Their iterators have:
xx.__iter__().__next__()
or
xxIterator = xx.__iter__()
xxIterator.__next__()
xxIterator.__next__()
xxIterator.__next__()
xxIterator.__next__()
xxIterator.__next__()
That's also what your quoted paragraph states:
| It then repeatedly calls the next() method
| (__next__() method in Python 3.x) of the iterator
--
Robin Koch
--
https://mail.python.org/mailman/listinfo/python-list
