Method returning an Iterable Object

James Mills prologic at shortcircuit.net.au
Tue Jan 27 04:33:22 CET 2009


On Tue, Jan 27, 2009 at 1:16 PM, Anjanesh Lekshminarayanan
<mail at anjanesh.net> wrote:
> But how come a raise StopIteration in the next() method doesnt need to
> be caught ? It works without breaking.

Because this exception is specially dealt
with when iterating over an iterator. The
"raise StopIteration" is what causes the
iteration to stop.

Consider:

>>> x = EveryOther(xrange(10))
>>> x.next()
0
>>> x.next()
2
>>> x.next()
4
>>> x.next()
6
>>> x.next()
8
>>> x.next()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "foo.py", line 12, in next
    raise StopIteration
StopIteration
>>> x = EveryOther(xrange(10))
>>> list(x)
[0, 2, 4, 6, 8]
>>>

cheers
James



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