CODEWITHSUNDEEP
pythoniterator
ThunderPhoenix
ThunderPhoenix

Reputation: 1883

Should an iterator be defined as another class?

Suppose we have this class definition:

class Series(object):
    def __init__(self, low, high):
        self.current = low
        self.high = high

    def __iter__(self):
        return self

    def __next__(self):
        if self.current > self.high:
            raise StopIteration
        else:
            self.current += 1
            return self.current - 1

In my opinion, this implementation is logically wrong. Indeed, we cannot have two independant iterators of this class:

s = Series(1,10)
it1 = iter(s)
print(next(it1))     # prints 1

it2 = iter(s)
print(next(it2))     # should print 1 but it prints 2

So my question is: Is it necessary to define another class for series_iterator in order to implement it well, or there is a way to implement a iterable and its iterator as the same class?

Upvotes: 2

Views: 486

Answers (1)

L3viathan
L3viathan

Reputation: 27283

So my question is: Is it necessary to define another class for series_iterator in order to implement it well?

No:

class Series:
    def __init__(self, low, high):
        self.low = low
        self.high = high

    def __iter__(self):
        current = self.low
        while current <= self.high:
            current += 1
            yield current - 1

By making __iter__ a generator, you don't have to define a new class for proper iterable behaviour. This won't always solve everything, since it's not as powerful as a seperate class, but in a large amount of cases, it's more than enough — and clearer.

Note that you don't have to implement __next__ now — that is already defined for you on the generator type.

Upvotes: 4

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