bpo-45995: add "z" format specifer to coerce negative 0 to zero#30049

belm0

This option coerces negative zero into zero after rounding to the format precision.
Covers formatting of standard fraction types (float, Decimal, complex) via str.format(), built-in format(), and f-strings. Old-style string interpolation
is not supported.

https://www.python.org/dev/peps/pep-0682/

https://bugs.python.org/issue45995

github-actions

This PR is stale because it has been open for 30 days with no activity.

mdickinson

Removing the stale label; discussion is ongoing on the bug tracker.

mdickinson

Update: the PEP has been accepted - https://discuss.python.org/t/accepting-pep-682-format-specifier-for-signed-zero/14088

We should aim to get this reviewed and in by the next (and final) alpha release of 3.11, due April 5th.

mdickinson

Hi @belm0. Here's a first-pass review; apologies for taking so long to get to this.

Most of the comments are nitpick-level. The big exception is the Decimal code, where I think there's still significant work to do.

bedevere-bot

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.

mdickinson

@ericvsmith: if you have any bandwidth to look over the code at some point before the first 3.11 beta, I'd appreciate your input.

belm0

Thank you for the thorough review!

I'm bogged down a bit and it may take a week or so to reconcile the comments.

Hoping to get this merged for the next (final) alpha.

3.11.0 alpha 7: Tuesday, 2022-04-05
3.11.0 beta 1: Friday, 2022-05-06

This covers str.format() and f-strings. Old-style string interpolation is not supported. TODO: Decimal support

mdickinson

Here's a second-pass review. We're getting there, but there are still a couple of bugs to resolve.

Co-authored-by: Mark Dickinson <dickinsm@gmail.com>

mdickinson

Thank you for the updates! This looks ready to merge to me. I've been running some automated tests that cover a wide variety of combinations, and haven't yet managed to break this. :-)

A bit off-topic: I do think we're introducing some DRY-type technical debt into _decimal.c, though for this PR I don't see an easy alternative. For the future, there's scope for some cleanup after lifting the formatting machinery from libmpdec to _decimal.c. That's for another day, though.

ericvsmith

Other than possibly adding a credit in the blurb, this looks good to me.

ghost

Commit authors are required to sign the Contributor License Agreement.

belm0

using file edit from the github UI appears to have angered CLA bot and bedevere

ericvsmith

using file edit from the github UI appears to have angered CLA bot and bedevere

I think it's related to the bpo to github issues migration. I'll see what I can figure out.

mdickinson

The "CLA Signing" check doesn't seem to be required for merging. Given that we know that CLA signing has occurred, I think we should be okay to merge. I've reported the failure to @ambv.

The implementation of PEP 682 was completed in python/cpython#30049.

belm0 requested a review from isidentical as a code owner December 11, 2021 13:24

the-knights-who-say-ni added the CLA signed label Dec 11, 2021

bedevere-bot added the awaiting review label Dec 11, 2021

belm0 marked this pull request as draft December 11, 2021 13:24

belm0 force-pushed the format_negative_zero branch from 97a033b to 8ff811f Compare December 11, 2021 13:44

belm0 marked this pull request as ready for review December 14, 2021 13:23

belm0 requested a review from rhettinger as a code owner December 14, 2021 13:23

belm0 commented Dec 18, 2021

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github-actions Bot added the stale Stale PR or inactive for long period of time. label Jan 18, 2022

taleinat requested a review from mdickinson January 18, 2022 07:38

mdickinson removed the stale Stale PR or inactive for long period of time. label Jan 22, 2022

belm0 force-pushed the format_negative_zero branch from 1bfb289 to bb4d5f1 Compare February 4, 2022 02:46

mdickinson suggested changes Mar 13, 2022

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bedevere-bot removed the awaiting review label Mar 13, 2022

bedevere-bot added the awaiting changes label Mar 13, 2022

ericvsmith reviewed Mar 13, 2022

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belm0 commented Mar 15, 2022

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belm0 and others added 7 commits March 19, 2022 14:57

bpo-45995: add "z" format specifer to coerce negative 0 to zero …

a633e88

This covers str.format() and f-strings. Old-style string interpolation is not supported. TODO: Decimal support

formatting

636da05

implementation for Decimal

3f4085d

📜🤖 Added by blurb_it.

68a049e

consistent flag names

ad32be5

add test case for integer value with z option

3dcaf5f

reference pending PEP

6b9ab3b

clarify Decimal strategy

2a24e61

belm0 commented Mar 23, 2022

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mdickinson reviewed Apr 5, 2022

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belm0 and others added 3 commits April 7, 2022 09:14

fix Decimal format parsing

0cbff6a

fix Decimal when no precision is specified

8e7b51c

fix comment typo …

418ab76

Co-authored-by: Mark Dickinson <dickinsm@gmail.com>

belm0 requested a review from mdickinson April 7, 2022 12:52

mdickinson approved these changes Apr 11, 2022

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bedevere-bot added awaiting merge and removed awaiting change review labels Apr 11, 2022

ericvsmith reviewed Apr 11, 2022

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ericvsmith approved these changes Apr 11, 2022

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add attribution to news blurb

3ee6f6b

ericvsmith added skip issue CLA signed and removed CLA signed labels Apr 11, 2022

mdickinson merged commit b0b836b into python:main Apr 11, 2022

bedevere-bot removed the awaiting merge label Apr 11, 2022

mdickinson added a commit to mdickinson/peps that referenced this pull request Apr 11, 2022

Mark PEP 682 as final. …

89fcfb2

The implementation of PEP 682 was completed in python/cpython#30049.

mdickinson mentioned this pull request Apr 11, 2022

PEP 682: Change status to Final python/peps#2513

Merged

belm0 deleted the format_negative_zero branch April 11, 2022 14:40

JelleZijlstra pushed a commit to python/peps that referenced this pull request Apr 11, 2022

PEP 682: Mark as final (#2513) …

2c4d71f

The implementation of PEP 682 was completed in python/cpython#30049.

mdickinson mentioned this pull request Apr 11, 2022

string formatting: normalize negative zero #90153

Closed

navytux mentioned this pull request Apr 30, 2023

"z" format specifier is treated differently in unicode and bytes #104018

Closed

ericvsmith mentioned this pull request Jan 25, 2024

Possible memory leak in _cdecimal.c with 'z' format #114563

Closed

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belm0 commented Dec 11, 2021 •

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