I'm creating a generator that gets consumed by another function, but I'd still like to know how many items were generated:

lines = (line.rstrip('\n') for line in sys.stdin)
process(lines)
print("Processed {} lines.".format( ? ))

The best I can come up with is to wrap the generator with a class that keeps a count, or maybe turn it inside out and send() things in. Is there an elegant and efficient way to see how many items a generator produced when you're not the one consuming it in Python 2?

Edit: Here's what I ended up with:

class Count(Iterable):
    """Wrap an iterable (typically a generator) and provide a ``count``
    field counting the number of items.

    Accessing the ``count`` field before iteration is finished will
    invalidate the count.
    """
    def __init__(self, iterable):
        self._iterable = iterable
        self._counter = itertools.count()

    def __iter__(self):
        return itertools.imap(operator.itemgetter(0), itertools.izip(self._iterable, self._counter))

    @property
    def count(self):
        self._counter = itertools.repeat(self._counter.next())
        return self._counter.next()
python count generator
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