Hello,
On Thu, Oct 21, 2010 at 12:26:50PM +0000, Steven
D'Aprano wrote:
> I know what you're thinking: "it's easy to cache
> the next result, and return it on the next
> call". But iterators can also be dependent on
> the time that they are called, like in this
> example:
>
> def evening_time():
> while 1:
> yield time.strftime("%H:%m") # e.g. "23:20"
When working with things like this you should
anyway use some lock/sync/transaction, so that
prefetching iterator will most probably be OK
unless you've fundamentally screwed your code's
logics.
WRT the prefetcher, I'd use smth like this:
> def rand_gen():
> x = random.random()
> while x < 0.9:
> yield x
> x = random.random()
>
> class prefetcher:
> def __init__(self, i):
> self.i = i
> self.s = False
> self._prefetch()
> def _prefetch(self):
> try: self.n = self.i.next()
> except StopIteration: self.s = True
> def has_next(self): return not self.s
> def next(self):
> if self.s: raise StopIteration()
> else:
> n = self.n
> self._prefetch()
> return n
> def __iter__(self): return self
>
> rand_pre = prefetcher(rand_gen())
> while rand_pre.has_next(): print rand_pre.next()
--
With best regards,
xrgtn
--
http://mail.python.org/mailman/listinfo/python-list
