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Improve syntax error for mixing keyword/positional in max patterns #88622

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pablogsal opened this issue Jun 18, 2021 · 6 comments
Closed

Improve syntax error for mixing keyword/positional in max patterns #88622

pablogsal opened this issue Jun 18, 2021 · 6 comments

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@pablogsal
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BPO 44456
Nosy @pablogsal, @miss-islington, @brandtbucher
PRs
  • bpo-44456: Improve the syntax error when mixing keyword and positional patterns #26793
  • [3.10] bpo-44456: Improve the syntax error when mixing keyword and positional patterns (GH-26793) #26900
    		•

    Note: these values reflect the state of the issue at the time it was migrated and might not reflect the current state.

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    GitHub fields:

    assignee = None
closed_at = <Date 2021-06-24.15:36:01.476>
created_at = <Date 2021-06-18.21:07:47.426>
labels = []
title = 'Improve syntax error for mixing keyword/positional in max patterns'
updated_at = <Date 2021-06-24.15:36:05.975>
user = 'https://github.com/pablogsal'

    bugs.python.org fields:

    activity = <Date 2021-06-24.15:36:05.975>
actor = 'pablogsal'
assignee = 'none'
closed = True
closed_date = <Date 2021-06-24.15:36:01.476>
closer = 'pablogsal'
components = []
creation = <Date 2021-06-18.21:07:47.426>
creator = 'pablogsal'
dependencies = []
files = []
hgrepos = []
issue_num = 44456
keywords = ['patch']
message_count = 6.0
messages = ['396088', '396090', '396091', '396100', '396493', '396495']
nosy_count = 3.0
nosy_names = ['pablogsal', 'miss-islington', 'brandtbucher']
pr_nums = ['26793', '26900']
priority = 'normal'
resolution = 'fixed'
stage = 'resolved'
status = 'closed'
superseder = None
type = None
url = 'https://bugs.python.org/issue44456'
versions = []
    @pablogsal
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    This got me confused for a sec when doing some live demo:

    >>> match x:
...    case A(y=1, foo):
  File "<stdin>", line 2
    case A(y=1, foo):
                   ^
SyntaxError: invalid syntax

    I propose to improve this to:

    >>> match x:
...    case A(y=1, foo):
  File "<stdin>", line 2
    case A(y=1, foo):
                ^^^
SyntaxError: cannot mix keyword patterns and positional patterns

    @pablogsal
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    Btw, I noticed this is allowed:

    >>> match x:
...    case A(foo, t=3):
...        ...
...

    but this is not:

    >>> match x:
...    case A(foo=3, t):

    Is that on pourpose?

    @pablogsal
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    If this is supposed to mirror function calls, maybe the error should be::

    >>> match a:
...    case A(foo=3, t):
  File "<stdin>", line 2
    case A(foo=3, t):
                  ^
SyntaxError: positional patterns follow keyword patterns

    @brandtbucher
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    Yep, it's intentional.

    And yep, I like the new error message better. :)

    @pablogsal
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    New changeset 0acc258 by Pablo Galindo in branch 'main':
    bpo-44456: Improve the syntax error when mixing keyword and positional patterns (GH-26793)
    0acc258

    @miss-islington
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    New changeset 11f1a30 by Miss Islington (bot) in branch '3.10':
    bpo-44456: Improve the syntax error when mixing keyword and positional patterns (GH-26793)
    11f1a30

    @ezio-melotti ezio-melotti transferred this issue from another repository Apr 10, 2022
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    3 participants
    @pablogsal @miss-islington @brandtbucher