On Thu, Jan 23, 2014 at 2:24 PM, Keith Winston <keithw...@gmail.com> wrote:
> On Thu, Jan 23, 2014 at 7:05 AM, eryksun <eryk...@gmail.com> wrote:
>> Generally you'll make `__iter__` a generator, so you don't have to
>> worry about implementing `__next__`. Also, the built-in function
>> `next` was added in 2.6, so you don't have to worry about the method
>> name difference between 2.x and 3.x, either.
>
> I'm now realizing I don't understand this comment at all. First, there
> IS a __iter__ method in the example: does the presence of such make it
> a generator already, or is it a usage thing, or something else? I
> don't yet completely understand the difference/point... or maybe you
> mean inherit the generator class?
Sorry, sloppy language. You'll make `__iter__` a generator *function*
that returns a generator, which is an iterator (i.e. has a `__next__`
method). This works in 2.6+ and 3.x without needing any kludges or
2to3. For example:
class MyIter:
def __init__(self, thelist):
self.thelist = thelist
def __iter__(self):
for item in self.thelist:
yield item
my_iter = MyIter(['a', 'b'])
it = iter(my_iter)
>>> type(it)
<class 'generator'>
>>> next(it)
'a'
>>> next(it)
'b'
>>> list(it) # exhausted
[]
> Second: you state that I don't have to worry about the name
> difference, but when I changed the method name from next to __next__
> it worked in 3.3. So what's your point here?
The 2nd statement in my original comment was contingent on the first,
which I apparently failed to clarify in the followup.
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