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Error in Format Specification Mini-Language concerning precision_with_grouping in 3.14 #134449

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jonathanpoelen opened this issue May 21, 2025 · 4 comments
Open

Error in Format Specification Mini-Language concerning precision_with_grouping in 3.14 #134449

jonathanpoelen opened this issue May 21, 2025 · 4 comments
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3.14 bugs and security fixes 3.15 new features, bugs and security fixes docs Documentation in the Doc dir type-bug An unexpected behavior, bug, or error

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@jonathanpoelen
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jonathanpoelen commented May 21, 2025 •
edited by bedevere-app bot
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Documentation

On this page: https://docs.python.org/3.14/library/string.html#grammar-token-format-spec-format_spec

format_spec:             [options][width_and_precision][type]
options:                 [[fill]align][sign]["z"]["#"]["0"]
fill:                    <any character>
align:                   "<" | ">" | "=" | "^"
sign:                    "+" | "-" | " "
width_and_precision:     [width_with_grouping][precision_with_grouping]
width_with_grouping:     [width][grouping]
precision_with_grouping: "." [precision][grouping]
width:                   digit+
precision:               digit+
grouping:                "," | "_"
type:                    "b" | "c" | "d" | "e" | "E" | "f" | "F" | "g"
                         | "G" | "n" | "o" | "s" | "x" | "X" | "%"

The precision_with_grouping syntaxe is wrong, because it accepts . without precision or grouping. But

>>> f'{1234.1234:.f}'
Traceback (most recent call last):
  File "<python-input-17>", line 1, in <module>
    f'{1234.1234:.f}'
      ^^^^^^^^^^^^^^
ValueError: Format specifier missing precision

(The error does not mention grouping either)

The right syntax should be

precision_with_grouping: "." precision [grouping] | "." grouping

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@jonathanpoelen jonathanpoelen added the docs Documentation in the Doc dir label May 21, 2025
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picnixz commented May 23, 2025

cc @skirpichev This is something we did right? I don't remember the issue/PR

@picnixz picnixz added type-bug An unexpected behavior, bug, or error 3.14 bugs and security fixes 3.15 new features, bugs and security fixes labels May 23, 2025
@skirpichev
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Yes, it's not accurate, see #125304 (review). I forgot that, lets fix this.

@jonathanpoelen, would you like to propose a pr?

@skirpichev skirpichev self-assigned this May 23, 2025
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I'll let you do the pr :)

skirpichev added a commit to skirpichev/cpython that referenced this issue May 24, 2025
@skirpichev
pythongh-134449: fix grammar for precision_with_grouping in format de…
ada07e7 
…scription

This amends f39a07b.  Thanks to Jonathan Poelen.
@bedevere-app bedevere-app bot mentioned this issue May 24, 2025
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@skirpichev skirpichev removed their assignment May 25, 2025
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PR is ready to review: #134608

picnixz pushed a commit that referenced this issue Jun 2, 2025
@skirpichev
gh-134449: fix grammar for precision_with_grouping in format descri…
7828d52 
…ption (#134608)

This amends commit f39a07b.
miss-islington pushed a commit to miss-islington/cpython that referenced this issue Jun 2, 2025
@skirpichev @miss-islington
pythongh-134449: fix grammar for precision_with_grouping in format …
43b14dd 
…description (pythonGH-134608)

This amends commit f39a07b.
(cherry picked from commit 7828d52)

Co-authored-by: Sergey B Kirpichev <skirpichev@gmail.com>
@bedevere-app bedevere-app bot mentioned this issue Jun 2, 2025
Merged
picnixz pushed a commit that referenced this issue Jun 2, 2025
@miss-islington @skirpichev
[3.14] gh-134449: fix grammar for precision_with_grouping in format…
16d5bdd 
… description (GH-134608) (#135015)

gh-134449: fix grammar for `precision_with_grouping` in format description (GH-134608)

This amends commit f39a07b.
(cherry picked from commit 7828d52)

Co-authored-by: Sergey B Kirpichev <skirpichev@gmail.com>
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