> def consume2(iterator, n): # the approved proposal (see #7764)
> if n is None:
> collections.deque(iterator, maxlen=0)
> else:
> next(islice(iterator, n, n), None)
FWIW, the deque() approach becomes even faster in Py2.7 and Py3.1
which has a high-speed path for the case where maxlen is zero.
Here's a snippet from Modules/_collectionsmodule.c:
/* Run an iterator to exhaustion. Shortcut for
the extend/extendleft methods when maxlen == 0. */
static PyObject*
consume_iterator(PyObject *it)
{
PyObject *item;
while ((item = PyIter_Next(it)) != NULL) {
Py_DECREF(item);
}
Py_DECREF(it);
if (PyErr_Occurred())
return NULL;
Py_RETURN_NONE;
}
This code consumes an iterator to exhaustion.
It is short, sweet, and hard to beat.
Raymond
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