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Error in Format Specification Mini-Language concerning precision_with_grouping in 3.14 #134449
Description
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
Activity
picnixz commentedon May 23, 2025
cc @skirpichev This is something we did right? I don't remember the issue/PR
skirpichev commentedon May 23, 2025
Yes, it's not accurate, see #125304 (review). I forgot that, lets fix this.
@jonathanpoelen, would you like to propose a pr?
jonathanpoelen commentedon May 24, 2025
I'll let you do the pr :)
pythongh-134449: fix grammar for precision_with_grouping in format de…
skirpichev commentedon May 25, 2025
PR is ready to review: #134608
gh-134449: fix grammar for `precision_with_grouping` in format descri…
pythongh-134449: fix grammar for `precision_with_grouping` in format …
[3.14] gh-134449: fix grammar for `precision_with_grouping` in format…
skirpichev commentedon Jun 24, 2025
#132205 was created before and was slightly better. Anyway, this is closed.
pythongh-134449: fix grammar for `precision_with_grouping` in format …
pythongh-134449: fix grammar for `precision_with_grouping` in format …
pythongh-134449: fix grammar for `precision_with_grouping` in format …