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gh-145239: Accept unary plus literal pattern - #148566

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johnslavik:gh-145239-accept-unary-plus-literal-pattern
Apr 23, 2026
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gh-145239: Accept unary plus literal pattern#148566
Eclips4 merged 10 commits into
python:mainfrom
johnslavik:gh-145239-accept-unary-plus-literal-pattern

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@johnslavik

@johnslavikjohnslavik commented Apr 14, 2026•
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LMK if you'd like the tests shortened. I copy-pasted the existing cases, but I'm tempted to shorten it drastically. You decide!

For example, I don't see the point in self.assertEqual on x.

@johnslavik
pythongh-145239: Accept unary plus in match literal patterns
004646e
Add '+' alternatives to signed_number and signed_real_number grammar
rules, mirroring how unary minus is already handled. Unary plus is a
no-op on numbers so the value is returned directly without wrapping in
a UnaryOp node.
@johnslavik
pythongh-145239: Add tests for unary plus in match literal patterns
b30bc97
Mirror the existing negative-number tests (095-110) for positive
numbers: integers, floats, imaginary, and complex patterns.
@johnslavik
pythongh-145239: Add NEWS entry
5bb1a93
@johnslavik
Add 1e1000 case
ea2a224
@bedevere-appbedevere-appBot mentioned this pull request Apr 14, 2026
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@johnslavik
Add exclusion to Lib/test/.ruff.toml
a54b92d
Assuming astral-sh/ruff#16394 (comment) is still correct, there's no other way around
@AlexWaygood
AlexWaygood removed their request for review April 14, 2026 17:36
@sunmy2019

sunmy2019 commented Apr 14, 2026

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You may also want to update this doc.

https://github.com/python/cpython/blob/bdb0b361926f225a06f1726c278c27346f3c524a/Doc/reference/compound_stmts.rst#literal-patterns

@johnslavik
johnslavik requested a review from encukouApril 14, 2026 18:15
@johnslavik

johnslavik commented Apr 14, 2026•
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Fun fact is that technically -+1, ----1, or ++++1 are valid expressions but matching against that still isn't possible. However, nobody needs this (which is why this is just a fun fact).

johnslavik
johnslavik commented Apr 22, 2026
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Comment threadLib/test/test_patma.py Outdated
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hugovk removed their request for review April 22, 2026 08:15
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johnslavik requested a review from Eclips4April 22, 2026 09:32
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Eclips4 approved these changes Apr 22, 2026
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LGTM. This makes pattern matching more consistent.
Will merge tomorrow if no one has anything to say.

@Eclips4
Eclips4 merged commit 448d7b9 into python:mainApr 23, 2026
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ljfp pushed a commit to ljfp/cpython that referenced this pull request Apr 25, 2026
@johnslavik@ljfp
pythongh-145239: Accept unary plus literal pattern (python#148566)
c1a69cf
Add '+' alternatives to signed_number and signed_real_number grammar
rules, mirroring how unary minus is already handled for pattern matching.
Unary plus is a no-op on numbers so the value is returned directly without
wrapping in a UnaryOp node.
@15r10nk15r10nk mentioned this pull request Jun 30, 2026
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@Twix1288Twix1288 mentioned this pull request Jun 30, 2026
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Twix1288 added a commit to Twix1288/cpython_opensource that referenced this pull request Jun 30, 2026
@Twix1288
Add NEWS entry forpythongh-148566
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Twix1288 added a commit to Twix1288/cpython_opensource that referenced this pull request Jun 30, 2026
@Twix1288
Add NEWS entry forpythongh-148566
a3d05fc
Twix1288 added a commit to Twix1288/cpython_opensource that referenced this pull request Jun 30, 2026
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Add NEWS entry forpythongh-148566
fe42b12
encukou
encukou reviewed Jul 1, 2026
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Comment threadGrammar/python.gram

imaginary_number[expr_ty]:
| imag=NUMBER { _PyPegen_ensure_imaginary(p, imag) }
| '+' imag=NUMBER { _PyPegen_ensure_imaginary(p, imag) }

@encukouencukouJul 1, 2026

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Since imaginary_number is always preceded by + or - already, this makes the following pass:

match1:
case1++1j:
pass

@johnslavik, do you want to fix this? Removing this case should do it.

@johnslavikjohnslavikJul 3, 2026

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Yes; I'll be back home from a trip soon and I'll fix it.

@johnslavikjohnslavikJul 5, 2026

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@encukou Let's revisit this at EuroPython sprints.

@encukouencukouJul 6, 2026

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I tend to be pretty busy at sprints; could you ask here?

@encukouencukouJul 27, 2026

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I filed #154776 for this.

@johnslavik
johnslavik deleted the gh-145239-accept-unary-plus-literal-pattern branch July 21, 2026 01:55
This was referenced Jul 27, 2026
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