[Python-Dev] who must makes FOR loop quicker
jjevnik at quantopian.com
Wed Aug 5 17:53:58 CEST 2015
The iterator is not revaluated, instead, it is constructing a single
iterator, in this case a list_iterator. The list_iterator looks at the
underyling list to know how to iterate so when you mutate the underlying
list, the list_iterator sees that. This does not mee the expression used to
generate the iterator was re-evaluated.
On Wed, Aug 5, 2015 at 11:25 AM, John Doe <z2911 at bk.ru> wrote:
> To pass by reference or by copy of - that is the question from hamlet.
> ("hamlet" - a community of people smaller than a village python3.4-linux64)
> xlist = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
> i = 0
> for x in xlist:
> print("\txlist[%d] = %d" % (i, x))
> if x%2 == 0 :
> print(xlist, "\n\n")
> i = i + 1
> So, catch the output and help me, PLEASE, improve the answer:
> Does it appropriate ALWAYS REevaluate the terms of the expression list in
> FOR-scope on each iteration?
> But if I want to pass ONCE a copy to FOR instead of a reference (as seen
> from an output) and reduce unreasonable reevaluation, what I must to do for
> Python-Dev mailing list
> Python-Dev at python.org
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the Python-Dev