gh-116241: Add support of multiple inheritance with typing.NamedTuple by serhiy-storchaka · Pull Request #31781 · python/cpython · GitHub

https://bugs.python.org/issue43923

Issue: NamedTuple can't inherit from another class #116241

I think this goes too far because it's not realistic to expect type checkers to support arbitrary base classes on NamedTuple. Also, there haven't been any user requests that I can see for multiple inheritance with anything other than Generic. So I'd prefer to merge the other PR that allows multiple inheritance with Generic only.

I think this goes too far because it's not realistic to expect type checkers to support arbitrary base classes on NamedTuple. Also, there haven't been any user requests that I can see for multiple inheritance with anything other than Generic. So I'd prefer to merge the other PR that allows multiple inheritance with Generic only.

I also think it makes sense to only allow multiple inheritance with Generic, for now. It's a smaller change; and, there should be opportunity to rethink it in the future if it turns out that people really need arbitrary multiple inheritance for whatever reason.

So, let's just close this?

people really need arbitrary multiple inheritance for whatever reason

Thanks for reopening! This looks like the case now indeed

Looks great! I ended up doing nearly exactly the same thing in some code of my own to get around this limitation.

Thank you @AlexWaygood and @gvanrossum. Updated to 3.14 and applied the suggestions.

Given that we've had multiple requests for this, I'm okay with landing it. But please get sign-offs from @gvanrossum and @JelleZijlstra before merging.

Let's do it! (I approve of the idea, I haven't carefully reviewed the code.)

I'm OK with this given the discussion on the issue; will take another look at the code soon.

Reminder for this: the 3.14 beta freeze is in two weeks.

That'd be great to have. I needed this more than once!

Suggested change

      
               .. versionchanged:: 3.14
          
               .. versionchanged:: next

Maybe add a test to check the order of the members as well when doing unpacking? And maybe test class Z(X, Y, NamedTuple)? (I don't know if this leads to a MRO incompatibilty though)

It will be error. This is tested in the next test.

This PR is stale because it has been open for 30 days with no activity.

Please consider addressing https://gist.github.com/johnslavik/4d0e22df6cb61868f74269fe7d401f5b.

This PR is stale because it has been open for 90 days with no activity.

Any progress?

This PR is stale because it has been open for 90 days with no activity.

serhiy-storchaka added the type-feature A feature request or enhancement label Mar 9, 2022

bedevere-bot added the awaiting core review label Mar 9, 2022

the-knights-who-say-ni added the CLA signed label Mar 9, 2022

JelleZijlstra mentioned this pull request Mar 10, 2022

bpo-43923: Allow NamedTuple multiple inheritance #31779

Closed

AlexWaygood added the topic-typing label Apr 13, 2022

FHTMitchell mannequin mentioned this pull request Apr 28, 2022

Can't create generic NamedTuple as of py3.9 #88089

Closed

serhiy-storchaka added 2 commits April 28, 2022 19:33

bpo-43923: Add support of generic typing.NamedTuple

939d5f0

bpo-43923: Add support of multiple inheritance with typing.NamedTuple

64f0c5f

serhiy-storchaka force-pushed the typing-namedtuple-multiple-inheritance branch from 637bdd3 to 64f0c5f Compare April 28, 2022 16:48

serhiy-storchaka marked this pull request as ready for review April 28, 2022 17:18

serhiy-storchaka requested review from Fidget-Spinner, JelleZijlstra and gvanrossum as code owners April 28, 2022 17:18

JelleZijlstra reviewed Apr 29, 2022

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serhiy-storchaka closed this Apr 30, 2022

serhiy-storchaka mentioned this pull request Mar 2, 2024

NamedTuple can't inherit from another class #116241

Open

serhiy-storchaka changed the title bpo-43923: Add support of multiple inheritance with typing.NamedTuple gh-116241: Add support of multiple inheritance with typing.NamedTuple Mar 2, 2024

serhiy-storchaka reopened this Mar 2, 2024

serhiy-storchaka requested a review from AlexWaygood as a code owner March 2, 2024 16:01

Merge branch 'main' into typing-namedtuple-multiple-inheritance

d4bc711

serhiy-storchaka force-pushed the typing-namedtuple-multiple-inheritance branch from 5077333 to d4bc711 Compare March 2, 2024 16:09

Jason-Y-Z approved these changes Mar 4, 2024

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CoolCat467 approved these changes Oct 9, 2024

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Fidget-Spinner removed their request for review October 9, 2024 14:36

AlexWaygood reviewed Oct 9, 2024

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Comment thread Doc/library/typing.rst Outdated

Comment thread Doc/whatsnew/3.13.rst Outdated

Comment thread Misc/NEWS.d/next/Library/2022-04-28-18-45-58.gh-issue-116241.hu9kRk.rst Outdated

gvanrossum reviewed Oct 9, 2024

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Comment thread Doc/library/typing.rst Outdated

serhiy-storchaka added 2 commits October 9, 2024 19:22

Merge branch 'main' into typing-namedtuple-multiple-inheritance

3159b21

Address review comments.

9d48f87

AlexWaygood approved these changes Oct 9, 2024

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bedevere-app Bot added awaiting merge and removed awaiting core review labels Oct 9, 2024

gvanrossum approved these changes Oct 9, 2024

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JelleZijlstra self-requested a review October 9, 2024 18:41

Merge branch 'main' into typing-namedtuple-multiple-inheritance

29dd4b7

picnixz reviewed May 8, 2025

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github-actions Bot added the stale Stale PR or inactive for long period of time. label Apr 10, 2026

serhiy-storchaka added 2 commits April 10, 2026 17:48

Merge branch 'main' into typing-namedtuple-multiple-inheritance

e44773c

Add also tests for unpacking.

ad78d99

serhiy-storchaka requested a review from AA-Turner as a code owner April 10, 2026 15:03

johnslavik self-requested a review April 10, 2026 15:05

johnslavik reviewed Apr 10, 2026

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johnslavik removed the stale Stale PR or inactive for long period of time. label Apr 13, 2026

serhiy-storchaka marked this pull request as draft April 13, 2026 17:58

bedevere-app Bot removed the awaiting merge label Apr 13, 2026

github-actions Bot added the stale Stale PR or inactive for long period of time. label Jul 12, 2026

github-actions Bot removed the stale Stale PR or inactive for long period of time. label Jul 18, 2026

github-actions Bot added the stale Stale PR or inactive for long period of time. label Oct 19, 2026

-                      for base in bases:
-                          if base is not _NamedTuple and base is not Generic:
-                              raise TypeError(
-                                  'can only inherit from a NamedTuple type and Generic')

                     disallowed in Python 3.15. To create a NamedTuple class with 0 fields,
                     use ``class NT(NamedTuple): pass`` or ``NT = NamedTuple("NT", [])``.
+                 .. versionchanged:: 3.14

+                      self.assertEqual(a.y, 5)
+                      self.assertEqual(len(a), 1)
+                      class Y(A, NamedTuple):

gh-116241: Add support of multiple inheritance with typing.NamedTuple by serhiy-storchaka · Pull Request #31781 · python/cpython · GitHub

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gh-116241: Add support of multiple inheritance with typing.NamedTuple - #31781

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