on 18.04.2007 07:39 Steven D'Aprano said the following:
> I thought that an iterator was any object that follows the iterator
replace object with "instance of a class", i.e. the relevant methods are
looked up in the __class__ not in the instance (I think).
I had the same troubles trying to dynamically reassign a __call__ method...
> protocol, that is, it has a next() method and an __iter__() method.
>
> But I'm having problems writing a class that acts as an iterator. I have:
>
> class Parrot(object):
> def __iter__(self):
> return self
> def __init__(self):
> self.next = self._next()
> def _next(self):
> for word in "Norwegian Blue's have beautiful plumage!".split():
> yield word
Try this::
class Parrot(object):
def __iter__(self):
return self
def __init__(self):
self.__class__.next = self._next().next # see post by I V
def _next(self):
for word in "Norwegian Blue's have beautiful plumage!".split():
yield word
This works but practically forces the class to be used as a singleton...
not very helpful :)
Better:
* use the '__iter__ returns/is a generator' way,
* or if you need the object to be the iterator, implement the next
method directly on the class::
class Parrot(object):
def _next(self):
for word in "Norwegian Blue's have beautiful plumage!".split():
yield word
def __iter__(self):
self.generator = self._next()
return self
def next(self):
return self.generator.next()
cheers,
stefan
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