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bpo-12159: document sys.maxsize limit in len() function reference #17934

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merged 1 commit into from
Jan 12, 2020
Merged

bpo-12159: document sys.maxsize limit in len() function reference #17934

merged 1 commit into from
Jan 12, 2020

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Zac-HD
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@Zac-HD Zac-HD commented Jan 10, 2020 •
edited by bedevere-bot
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See:

  • BPO-12159: "needs to be documented",
  • BPO-15718: added note to datamodel docs for __len__ method but not len(), and
  • BPO-21444: change request / wontfix

https://bugs.python.org/issue12159

@bedevere-bot bedevere-bot added docs Documentation in the Doc dir awaiting review labels Jan 10, 2020
@cool-RR
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cool-RR commented Jan 10, 2020

I think that this is a good addition to the documentation, but the example with range is weird. Maybe you mean that big ranges, such as range(10 ** 100) will be too big. That isn't clear from your text.

vstinner
vstinner reviewed Jan 10, 2020
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Doc/library/functions.rst Outdated
@@ -892,6 +892,9 @@ are always available. They are listed here in alphabetical order.
sequence (such as a string, bytes, tuple, list, or range) or a collection
(such as a dictionary, set, or frozen set).

**CPython implementation detail:** ``len`` raises :class:`OverflowError`
on inputs larger than :data:`sys.maxsize`, such as :class:`range`.
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Suggested change
on inputs larger than :data:`sys.maxsize`, such as :class:`range`.
on lengths larger than :data:`sys.maxsize`.

I don't understand the "such as range()" part. len(range(5)) returns 5, it doesn't fail with overflow?

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I've clarified that this is for cases such as range(2 ** 64).

vstinner
vstinner reviewed Jan 11, 2020
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@vstinner vstinner changed the title BPO-12159: document sys.maxsize limit in function reference for len() bpo-12159: document sys.maxsize limit in len() function reference Jan 11, 2020
vstinner
vstinner approved these changes Jan 11, 2020
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LGTM, but I would prefer to get a second review. @csabella @serhiy-storchaka @JulienPalard: What do you think of this len note?

csabella
csabella approved these changes Jan 12, 2020
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LGTM. Since this has been brought up multiple times, I think it's best to document it, especially since __len__ had a note added in the past. Thanks for the patch, @Zac-HD!

csabella
csabella requested changes Jan 12, 2020
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A Python core developer has requested some changes be made to your pull request before we can consider merging it. If you could please address their requests along with any other requests in other reviews from core developers that would be appreciated.

Once you have made the requested changes, please leave a comment on this pull request containing the phrase I have made the requested changes; please review again. I will then notify any core developers who have left a review that you're ready for them to take another look at this pull request.

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Zac-HD commented Jan 12, 2020

I have made the requested changes; please review again

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Thanks for making the requested changes!

@csabella, @vstinner: please review the changes made to this pull request.

@vstinner vstinner merged commit d7c7add into python:master Jan 12, 2020
@Zac-HD Zac-HD deleted the document-len-overflow branch January 12, 2020 10:33
shihai1991 pushed a commit to shihai1991/cpython that referenced this pull request Jan 31, 2020
@Zac-HD @shihai1991
bpo-12159: Document sys.maxsize limit in len() function reference (py…
a8074ea 
…thonGH-17934)
@Zac-HD Zac-HD mentioned this pull request Mar 28, 2020
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@cool-RR cool-RR mannequin mentioned this pull request Apr 29, 2022
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@csabella csabella Awaiting requested review from csabella

@vstinner vstinner Awaiting requested review from vstinner

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