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Groups > comp.lang.python > #106253
| From | Rob Gaddi <rgaddi@highlandtechnology.invalid> |
|---|---|
| Newsgroups | comp.lang.python |
| Subject | Re: Strange range |
| Date | 2016-04-01 20:21 +0000 |
| Organization | A noiseless patient Spider |
| Message-ID | <ndml7n$494$1@dont-email.me> (permalink) |
| References | (2 earlier) <ndlvrt$1hlp$1@gioia.aioe.org> <mailman.311.1459521083.28225.python-list@python.org> <87lh4xjt37.fsf@elektro.pacujo.net> <mailman.327.1459540903.28225.python-list@python.org> <874mblrsr1.fsf@elektro.pacujo.net> |
Marko Rauhamaa wrote:
> Erik <python@lucidity.plus.com>:
>
>> On 01/04/16 15:34, Marko Rauhamaa wrote:
>>> Chris Angelico <rosuav@gmail.com>:
>>>
>>>> *A range object is not an iterator.*
>>>
>>> We now have learned as much.
>>>
>>> However, doesn't that extra level of indirection seem like an odd
>>> choice?
>>
>> [...]
>>
>> If you write your own class which has an __iter__ method, would you
>> [...] expect both iterators to be independent and both return the
>> 'foo', 'bar', 'baz' sequence (where that is the hypothetical result of
>> iterating over your object)?
>>
>> If you now replace MyClass() with range(10), why would you expect the
>> two iterators to be related?
>
> I simply had thought of range() returning an iterator. I would expect an
> iterator to behave like one.
>
> There's a bit of a cognitive dissonance between iterables and iterators.
> On the one hand, they behave identically in many contexts. On the other
> hand, the distinction is crucial in some special cases.
You're missing a key point. All (well-behaved) iterators are iterables,
with their __iter__ method returning themselves.
for x in y:
...
implies:
try:
_it = iter(y)
while True:
x = next(_it)
...
except StopIteration:
pass
That's true for any iterable y, including a y which is itself an
iterator. You still call iter() on it, and get _it, the iterator over
y, which if y is an iterator is the same thing as y.
--
Rob Gaddi, Highland Technology -- www.highlandtechnology.com
Email address domain is currently out of order. See above to fix.
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Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 16:15 +0300
Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-02 00:24 +1100
Re: Strange range Steven D'Aprano <steve@pearwood.info> - 2016-04-02 00:26 +1100
Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 17:12 +0300
Re: Strange range Random832 <random832@fastmail.com> - 2016-04-01 10:39 -0400
Re: Strange range Fabien <fabien.maussion@gmail.com> - 2016-04-01 16:16 +0200
Re: Strange range Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-04-01 17:28 +0300
Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-02 01:31 +1100
Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 17:34 +0300
Re: Strange range Jussi Piitulainen <jussi.piitulainen@helsinki.fi> - 2016-04-01 17:44 +0300
Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-02 01:45 +1100
Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 18:43 +0300
Re: Strange range Erik <python@lucidity.plus.com> - 2016-04-01 20:58 +0100
Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 23:14 +0300
Re: Strange range Rob Gaddi <rgaddi@highlandtechnology.invalid> - 2016-04-01 20:21 +0000
Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 23:44 +0300
Re: Strange range Steven D'Aprano <steve@pearwood.info> - 2016-04-02 21:09 +1100
Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-02 13:48 +0300
Re: Strange range Ned Batchelder <ned@nedbatchelder.com> - 2016-04-02 12:47 -0700
Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-02 23:44 +0300
Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-03 07:05 +1000
Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-03 00:40 +0300
Re: Strange range Ned Batchelder <ned@nedbatchelder.com> - 2016-04-02 14:50 -0700
Re: Strange range Stephen Hansen <me+python@ixokai.io> - 2016-04-02 23:43 -0700
Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-03 09:58 +0300
Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-03 17:10 +1000
Re: Strange range Ethan Furman <ethan@stoneleaf.us> - 2016-04-03 09:28 -0700
Re: Strange range Mark Lawrence <breamoreboy@yahoo.co.uk> - 2016-04-04 13:21 +0100
Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-03 17:08 +1000
Re: Strange range Steven D'Aprano <steve@pearwood.info> - 2016-04-03 14:43 +1000
Re: Strange range Random832 <random832@fastmail.com> - 2016-04-03 01:20 -0400
Re: Strange range Steven D'Aprano <steve@pearwood.info> - 2016-04-03 15:28 +1000
Re: Strange range Marko Rauhamaa <marko@pacujo.net> - 2016-04-01 17:32 +0300
Re: Strange range Random832 <random832@fastmail.com> - 2016-04-01 10:42 -0400
Re: Strange range Chris Angelico <rosuav@gmail.com> - 2016-04-02 01:50 +1100
Re: Strange range Ian Kelly <ian.g.kelly@gmail.com> - 2016-04-01 08:52 -0600
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