Improve itertools docs with clearer examples of pure python equivalent code.
diff --git a/Doc/library/functions.rst b/Doc/library/functions.rst
index ced3745..e5d4a99 100644
--- a/Doc/library/functions.rst
+++ b/Doc/library/functions.rst
@@ -1367,10 +1367,10 @@
def zip(*iterables):
# zip('ABCD', 'xy') --> Ax By
sentinel = object()
- iterables = [iter(it) for it in iterables]
- while iterables:
+ iterators = [iter(it) for it in iterables]
+ while iterators:
result = []
- for it in iterables:
+ for it in iterators:
elem = next(it, sentinel)
if elem is sentinel:
return
diff --git a/Doc/library/itertools.rst b/Doc/library/itertools.rst
index 757823d..28625e8 100644
--- a/Doc/library/itertools.rst
+++ b/Doc/library/itertools.rst
@@ -557,16 +557,25 @@
iterables are of uneven length, missing values are filled-in with *fillvalue*.
Iteration continues until the longest iterable is exhausted. Equivalent to::
- def zip_longest(*args, fillvalue=None):
+ class ZipExhausted(Exception):
+ pass
+
+ def zip_longest(*args, **kwds):
# zip_longest('ABCD', 'xy', fillvalue='-') --> Ax By C- D-
- def sentinel(counter = ([fillvalue]*(len(args)-1)).pop):
- yield counter() # yields the fillvalue, or raises IndexError
+ fillvalue = kwds.get('fillvalue')
+ counter = len(args) - 1
+ def sentinel():
+ nonlocal counter
+ if not counter:
+ raise ZipExhausted
+ counter -= 1
+ yield fillvalue
fillers = repeat(fillvalue)
- iters = [chain(it, sentinel(), fillers) for it in args]
+ iterators = [chain(it, sentinel(), fillers) for it in args]
try:
- for tup in zip(*iters):
- yield tup
- except IndexError:
+ while iterators:
+ yield tuple(map(next, iterators))
+ except ZipExhausted:
pass
If one of the iterables is potentially infinite, then the :func:`zip_longest`