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Fix iter_index() to work with lists which do not support stop=None. #109306

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rhettinger merged 1 commit into from
Sep 12, 2023
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Fix iter_index() to work with lists which do not support stop=None. #109306

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11 changes: 11 additions & 0 deletions Doc/library/itertools.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -877,6 +877,7 @@ which incur interpreter overhead.
yield i
else:
# Fast path for sequences
stop = len(iterable) if stop is None else stop
i = start - 1
try:
while True:
Expand Down Expand Up @@ -1345,6 +1346,16 @@ The following recipes have a more mathematical flavor:
Traceback (most recent call last):
...
ValueError
>>> # Verify that both paths can find identical NaN values
>>> x = float('NaN')
>>> y = float('NaN')
>>> list(iter_index([0, x, x, y, 0], x))
[1, 2]
>>> list(iter_index(iter([0, x, x, y, 0]), x))
[1, 2]
>>> # Test list input. Lists do not support None for the stop argument
>>> list(iter_index(list('AABCADEAF'), 'A'))
[0, 1, 4, 7]
Comment on lines +1356 to +1358
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@serhiy-storchaka serhiy-storchaka Sep 12, 2023

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Was not list input already tested above, in list(iter_index([0, x, x, y, 0], x))?

If you want a separate test for list which does not involve NaN, it is better to move this test upper, just after list(iter_index(iter('AABCADEAF'), 'A', 1, 7)).


>>> list(sieve(30))
[2, 3, 5, 7, 11, 13, 17, 19, 23, 29]
Expand Down