On 12/10/2014 1:53 AM, Chris Angelico wrote:
On Wed, Dec 10, 2014 at 5:44 PM, Steven D'Aprano <st...@pearwood.info> wrote:
It would be nice if product iterators behaved like xrange() objects and
could perform "in" tests without exhausting the iterator, but they don't.
That's sad.
It'd be very difficult to do that in the general sense. But it should
be possible to have a multi-dimensional range object that behaves the
way Py3's range object does, including membership tests and stuff.
(Might already exist, for all I know.) That would do what the OP
wants, I think.
Itertools are general tools for building specialized objects.
itertools.product provides the iter method.
class ReitProd(): # untested
def __init__(self, reiterable, n):
self.reit = reiterable # must support 'in'
self.n = n
def __iter__(self):
return itertools.product(self.reit, repeat=self.n)
def __contains__(self, seq):
if len(seq) != self.n:
return False
for i, item in enumerate(it):
if item not in self.reit:
return False
return True
--
Terry Jan Reedy
--
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