Paul Hankin wrote:
> On Mar 10, 3:12 am, George Sakkis <[EMAIL PROTECTED]> wrote:
>> On Mar 9, 7:37 pm, Paul Hankin <[EMAIL PROTECTED]> wrote:
>>
>>
>>
>>> On Mar 9, 8:58 pm, duccio <[EMAIL PROTECTED]> wrote:
>>>> Someone knows if it's possible to make this __iter__ function with just
>>>> one 'yield' intead of two?
>>>> ...
>>>> def __iter__(self):
>>>> yield self #1
>>>> for n in self.childs:
>>>> for nn in n.__iter__():
>>>> yield nn #2
>>> Only one yield and shorter (but not really any simpler):
>>> from itertools import chain
>>> class Node:
>>> ...
>>> def __iter__(self):
>>> for x in chain([self], *self.childs):
>>> yield x
>> Actually this doesn't need a yield at all:
>>
>> class Node:
>> ...
>> def __iter__(self):
>> return chain([self], *self.childs)
>
> The two have slightly different behaviours: without the yield, iter is
> called immediately on every node in the tree as the iterators are
> built. With yield, iterators are built lazily, giving better
> behaviour.
generator expressions allow to save on the 'yield' while keeping the lazy
behavior, with either :
def __iter__(self):
return chain([self],(y for x in self.childs for y in x))
or
def __iter__(self):
return (y for x in chain([[self]],self.childs) for y in x)
BB
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