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mdickinson merged 15 commits intopython:mainfrommdickinson:fraction-format-d-presentation-type

Dec 16, 2023

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gh-67790: Support basic formatting for Fraction#111320

mdickinson merged 15 commits intopython:mainfrommdickinson:fraction-format-d-presentation-type

Dec 16, 2023

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mdickinson commentedOct 25, 2023•
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PR#100161 added fancy float-style formatting for theFraction type, but left us in a state where basic formatting for fractions (alignment, fill, thousands separators) still wasn't supported. For example, we can't currently specify a minimum width for a formatted fraction:

>>>format(Fraction(3,2),'20')Traceback (mostrecentcalllast):File"<stdin>",line1,in<module>File"/opt/local/Library/Frameworks/Python.framework/Versions/3.12/lib/python3.12/fractions.py",line427,in__format__raiseValueError(ValueError:Invalidformatspecifier'20'forobjectof type'Fraction'

This PR adds that basic formatting support, aiming for compatibility withint formatting. The basic formatting is active either with presentation typed, or with no explicit presentation type. For example, on this branch:

>>>x=Fraction(103993,33102)>>>f"{x:.<20}"# minimum width, fill and alignment'103993/33102........'>>>f"{x:_}"# thousands separators'103_993/33_102'>>>f"{x:+}"# sign specification'+103993/33102'>>>f"{x:+d}"# explicit 'd' presentation type'+103993/33102'>>>y=Fraction(22)>>>f"{y}"'22'>>>f"{y:#}"# alternate flag '#' forces an explicit denominator'22/1'

All of the above exceptf"{y}" currently giveValueError on main.

Some details:

Minimum width, fill character, alignment, the sign flag, and thousands separators are supported in the obvious way.
The zero-fill flag0 isnot supported (though it's still fine to use0 as a fill character in the normal way): it's not 100% clear what the semantics should be (should both the numerator and denominator be padded? Just the numerator?) or what value it would provide, so until someone comes up with valid use-cases that can help inform the semantics, I'm leaving this unsupported.
The alternate flag# forces a slash and denominator in the formatted output, even when the output is integer-valued. By default, the slash and denominator are left off for integer-valued fractions.

Pinging@ericvsmith for awareness.

Issue:Implement __format__ for Fraction #67790

📚 Documentation preview 📚:https://cpython-previews--111320.org.readthedocs.build/

mdickinson added3 commits

October 25, 2023 11:48

pythongh-67790: Add integer-style formatting for Fraction type

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Add docs

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Oct 25, 2023

Implement __format__ for Fraction#67790

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Add PR number

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mdickinson changed the title~~gh-67790: Support basic formatting inFraction.__format__~~gh-67790: Support basic formatting for Fraction

Oct 25, 2023

Restore original line spacing in docs

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Oct 25, 2023

gh-67790: Add integer-style formatting for fractions.Fractionmdickinson/cpython#2

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mdickinson commentedOct 25, 2023

@serhiy-storchaka @ericvsmith Would either of you be interested in reviewing?

mdickinson added2 commits

October 25, 2023 15:16

Remove 'float-style', since it's now too specific

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Tighten doc wording

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serhiy-storchaka commentedOct 25, 2023•
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float.__format__ does not supportd. On other hand,%d in printf-like formatting accept float, but truncate it. Would not it cause confusion? Users may (wrongly) suppose that thed format specifier always format a number as a decimal integer.

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Oct 25, 2023

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It is perhaps out of the scope of this PR or this issue, but it may be useful to provide options for:

output as improper fraction: 3/2 as1 1/2.
~~always output a fraction slash: 3/1 as3/1.~~ (already possible with the# modifier)
specify different symbol for fraction slash, e.g.:,÷ (U+00F7),⁄ (U+2044),∕ (U+2215),∶ (U+2236).

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Oct 25, 2023

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mdickinson commentedOct 25, 2023•
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@serhiy-storchaka Thank you for reviewing!

float.__format__ does not supportd. On other hand,%d in printf-like formatting accept float, but truncate it. Would not it cause confusion?

Hmm, possibly. Now that I look at it, we're adding two ways to do exactly the same thing (that is,format(f, s) andformat(f, s + 'd') do exactly the same thing wheres is a format specifier without a presentation type). That seems unnecessary.

What do you think about simply dropping thed support for now? So for exampleformat(f, '>.10') would still work butformat(f, '>.10d') wouldn't. Then we can still add support for ad presentation type in the future if that looks useful.

it may be useful to provide options for [...]

Yes, I think I'd rather leave these to a separate PR.

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serhiy-storchaka commentedOct 25, 2023

What do you think about simply dropping thed support for now?

Looks fine to me.

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LGTM

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ericvsmith commentedOct 25, 2023

What do you think about simply dropping thed support for now? So for exampleformat(f, '>.10') would still work butformat(f, '>.10d') wouldn't. Then we can still add support for ad presentation type in the future if that looks useful.

Actually, I think I'd require the "d", just in case we want to do somethings else entirely without it. But I don't feel strongly about it.

OTOH, note that for ints, the 'd' has no effect.

Merge branch 'main' into fraction-format-d-presentation-type

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serhiy-storchaka commentedDec 1, 2023

@mdickinson It LGTM if drop 'd' and "integer-like".

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mdickinson commentedDec 3, 2023

Thanks@serhiy-storchaka and@ericvsmith for feedback.

@ericvsmith

Actually, I think I'd require the "d", just in case we want to do somethings else entirely without it.

Yes, I can see a case both ways, and part of me wants to require a presentation type for all non-trivial formatting. Ithink this is close enough to the obvious one way to do formatting for Fractions that I'm happy for it to be the "default" formatting, so not require a "d". I'll make that change.

mdickinson added3 commits

December 3, 2023 09:55

Remove support for 'd' presentation type; don't refer to integer-style

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Fix single backtick

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Fix grammar - 'or' is better than 'and' here

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December 3, 2023 10:15

Tweak wording

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Update invalid format tests

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Fix a long line in the .rst source

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LGTM. Thanks, Mark!

Merge branch 'main' into fraction-format-d-presentation-type

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mdickinson merged commitfe479fb intopython:main

Dec 16, 2023

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mdickinson deleted the fraction-format-d-presentation-type branch

December 16, 2023 10:58

scoder added a commit to scoder/quicktions that referenced this pull request

Jan 10, 2024

Implement more general string formatting for Fraction, following CPyt…

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…hon 3.13.Seepython/cpython#111320

bmwiedemann pushed a commit to bmwiedemann/openSUSE that referenced this pull request

Jan 21, 2024

Update python-quicktions to version 1.16 / rev 10 via SR 1140281

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https://build.opensuse.org/request/show/1140281by user dirkmueller + anag+factory- update to 1.16:  * Formatting support was improved, following CPython 3.13a3 as    ofpython/cpython#111320  * Add support for Python 3.13 by using Cython 3.0.8 and calling    math.gcd().

bmwiedemann pushed a commit to bmwiedemann/openSUSE that referenced this pull request

Feb 7, 2024

Update python-quicktions to version 1.16 / rev 10 via SR 1140281

e8d2fb1

https://build.opensuse.org/request/show/1140281by user dirkmueller + anag+factory- update to 1.16:  * Formatting support was improved, following CPython 3.13a3 as    ofpython/cpython#111320  * Add support for Python 3.13 by using Cython 3.0.8 and calling    math.gcd().

bmwiedemann pushed a commit to bmwiedemann/openSUSE that referenced this pull request

Feb 7, 2024

Update python-quicktions to version 1.16 / rev 10 via SR 1140281

ce9d548

https://build.opensuse.org/request/show/1140281by user dirkmueller + anag+factory- update to 1.16:  * Formatting support was improved, following CPython 3.13a3 as    ofpython/cpython#111320  * Add support for Python 3.13 by using Cython 3.0.8 and calling    math.gcd().

aisk pushed a commit to aisk/cpython that referenced this pull request

Feb 11, 2024

pythongh-67790: Support basic formatting for Fraction (python#111320)

d385fe6

PRpython#100161 added fancy float-style formatting for the Fraction type,but left us in a state where basic formatting for fractions (alignment,fill, minimum width, thousands separators) still wasn't supported.This PR adds that support.---------Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

Glyphack pushed a commit to Glyphack/cpython that referenced this pull request

Sep 2, 2024

pythongh-67790: Support basic formatting for Fraction (python#111320)

f8d56b9

PRpython#100161 added fancy float-style formatting for the Fraction type,but left us in a state where basic formatting for fractions (alignment,fill, minimum width, thousands separators) still wasn't supported.This PR adds that support.---------Co-authored-by: Serhiy Storchaka <storchaka@gmail.com>

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mdickinson commentedOct 25, 2023•
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serhiy-storchaka commentedOct 25, 2023•
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