[Python-checkins] Add comment and improve variable name in roundrobin() (#4486)

Tue Nov 21 03:23:42 EST 2017

https://github.com/python/cpython/commit/337cbbace0a43f50fcd33ea4d3b7cb30733237db
commit: 337cbbace0a43f50fcd33ea4d3b7cb30733237db
branch: master
author: Raymond Hettinger <rhettinger at users.noreply.github.com>
committer: GitHub <noreply at github.com>
date: 2017年11月21日T00:23:34-08:00
summary:
Add comment and improve variable name in roundrobin() (#4486)
files:
M Doc/library/itertools.rst

diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst
index fa6c340bb7b..a91894059d0 100644
--- a/Doc/library/itertools.rst
+++ b/Doc/library/itertools.rst
@@ -753,15 +753,16 @@ which incur interpreter overhead.
 def roundrobin(*iterables):
 "roundrobin('ABC', 'D', 'EF') --> A D E B F C"
 # Recipe credited to George Sakkis
- pending = len(iterables)
+ num_active = len(iterables)
 nexts = cycle(iter(it).__next__ for it in iterables)
- while pending:
+ while num_active:
 try:
 for next in nexts:
 yield next()
 except StopIteration:
- pending -= 1
- nexts = cycle(islice(nexts, pending))
+ # Remove the iterator we just exhausted from the cycle.
+ num_active -= 1
+ nexts = cycle(islice(nexts, num_active))
 
 def partition(pred, iterable):
 'Use a predicate to partition entries into false entries and true entries'
