python / python/mypy

Allow keyword arguments when creating namedtuple

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bug topic-named-tuple
Dominant language
Python
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Description

Bug Report
The program:

from collections import namedtuple

Point = namedtuple(typename='Point', field_names=['x', 'y'])
p_1 = Point(2, 7)

The first line is marked by mypy:

Unexpected arguments to "namedtuple()" [misc]

I think it should be allowed to use argument names in the call.

The second line is marked so:

Too many arguments for "Point" [call-arg]

I think this is definitely a false positive.

(A clear and concise description of what the bug is.)

To Reproduce

# Ideally, a small sample program that demonstrates the problem.
# Or even better, a reproducible playground link https://mypy-play.net/ (use the "Gist" button)

Expected Behavior

Actual Behavior

Your Environment

  • Mypy version used: 1.7.1
  • Mypy command-line flags: None
  • Mypy configuration options from mypy.ini (and other config files): None
  • Python version used: 3.11.4

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the collections.namedtuple reproducer and run mypy on it to confirm both diagnostics. Trace how namedtuple calls and the generated Point constructor are analyzed; done means keyword arguments are accepted and the false-positive error on Point(2, 7) is gone.

Written by the indexing model from the issue text.

Assessment

Tech stack
python
Domain
devtools
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
43/100

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