Skip to content

PEP 795: Deep Immutability in Python #4468

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom
Open
TobiasWrigstad wants to merge 19 commits into
base: main
Choose a base branch
from
Open

PEP 795: Deep Immutability in Python #4468

TobiasWrigstad wants to merge 19 commits into from

Conversation

@TobiasWrigstad
Copy link

@TobiasWrigstad TobiasWrigstad commented Jun 19, 2025 •
edited by hugovk
Loading

Basic requirements (all PEP Types)

  • Read and followed PEP 1 & PEP 12
  • File created from the latest PEP template
  • PEP has next available number, & set in filename (pep-NNNN.rst), PR title (PEP 123: <Title of PEP>) and PEP header
  • Title clearly, accurately and concisely describes the content in 79 characters or less
  • Core dev/PEP editor listed as Author or Sponsor, and formally confirmed their approval
  • Author, Status (Draft), Type and Created headers filled out correctly
  • PEP-Delegate, Topic, Requires and Replaces headers completed if appropriate
  • Required sections included
    • Abstract (first section)
    • Copyright (last section; exact wording from template required)
  • Code is well-formatted (PEP 7/PEP 8) and is in code blocks, with the right lexer names if non-Python
  • PEP builds with no warnings, pre-commit checks pass and content displays as intended in the rendered HTML
  • Authors/sponsor added to .github/CODEOWNERS for the PEP

Standards Track requirements

  • PEP topic discussed in a suitable venue with general agreement that a PEP is appropriate
  • Suggested sections included (unless not applicable)
    • Motivation
    • Rationale
    • Specification
    • Backwards Compatibility
    • Security Implications
    • How to Teach This
    • Reference Implementation
    • Rejected Ideas
    • Open Issues
  • Python-Version set to valid (pre-beta) future Python version, if relevant
  • Any project stated in the PEP as supporting/endorsing/benefiting from the PEP formally confirmed such
  • Right before or after initial merging, PEP discussion thread created and linked to in Discussions-To and Post-History

📚 Documentation preview 📚: https://pep-previews--4468.org.readthedocs.build/pep-0795/

@TobiasWrigstad TobiasWrigstad requested a review from a team as a code owner June 19, 2025 06:16
@python-cla-bot
Copy link

python-cla-bot bot commented Jun 19, 2025 •
edited
Loading

All commit authors signed the Contributor License Agreement.

CLA signed

@TobiasWrigstad TobiasWrigstad force-pushed the pep795 branch 3 times, most recently from b2bf4aa to 7cedb55 Compare June 19, 2025 06:38
AA-Turner
AA-Turner reviewed Jun 19, 2025
View reviewed changes
@AA-Turner AA-Turner changed the title PEP 795: Add deep immutability to Python PEP 795: Deep Immutability in Python Jun 19, 2025
@AA-Turner AA-Turner added the new-pep A new draft PEP submitted for initial review label Jun 19, 2025
AA-Turner
AA-Turner reviewed Jun 19, 2025
View reviewed changes
peps/pep-0795/sharing1.png
Copy link
Member

@AA-Turner AA-Turner Jun 19, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Is there a programmatic/text source that this file was created from? If so, it would be useful to include that, and also consider using an SVG file rather than a PNG.

Copy link
Author

@TobiasWrigstad TobiasWrigstad Jun 19, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Hmm. We followed PEP12 which says:

peps/peps/pep-0012.rst

Lines 604 to 605 in b5ae2b1

Currently, SVG must be avoided due to compatibility issues with the
PEP build system.

Maybe this is outdated instructions?

Currently the file was extracted from Keynote which is macOS-only. We could redraw this in a more accessible format perhaps.

Copy link
Member

@AA-Turner AA-Turner Jun 19, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Yes, we can now support & prefer SVG files. If Keynote will export an SVG, that should be fine? I had wondered if you'd used e.g. TikZ or graphviz to make the image.

@AA-Turner
Copy link
Member

AA-Turner commented Jun 19, 2025

Please avoid force pushing, we squash-merge all PRs.

@hugovk
Copy link
Member

hugovk commented Jun 19, 2025 •
edited
Loading

For the next PEP, please wait until the initial PR is merged before opening the PEP discussion, because we want to share the official peps.python.org URL and not the PR preview that will be deleted at some point. (Pre-PEP discussions can be opened at any time.)

And especially please wait until the sponsor had confirmed sponsorship, as we the PEP number only gets officially assigned then and it can cause confusion to re-assign numbers later.

Please see PEP 1 for more details.

https://peps.python.org/pep-0001/#submitting-a-pep

Thank you!

@AA-Turner @mdboom
New email for Michael Droettboom
269ff9c 
Co-authored-by: Michael Droettboom <mdboom@gmail.com>
JelleZijlstra
JelleZijlstra reviewed Jun 19, 2025
View reviewed changes
mdboom
mdboom reviewed Jun 20, 2025
View reviewed changes
peps/pep-0795.rst Outdated

3. The type ``NotFreezable`` which is an empty type which cannot be made immutable and can be used as a super class to classes whose instances should not be possible to freeze

4. The type ``NotFreezableError`` which is raised on an attempt to mutate an immutable object
Copy link
Contributor

@mdboom mdboom Jun 20, 2025

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

Isn't this for an attempt to freeze and unfreezable object? Below, it says it raises a TypeError when trying to mutate an immutable object.

mjp41 and others added 5 commits December 19, 2025 12:05
@mjp41 @TobiasWrigstad
@xFrednet @matajoh
Revamp based on DPO (#15)
5f59e37 
See "Changes from the previous draft" for details.

--

Co-authored-by: Tobias Wrigstad <tobias.wrigstad@it.uu.se>
Co-authored-by: Fridtjof Stoldt <xFrednet@gmail.com>
Co-authored-by: Matthew Johnson <matajoh@users.noreply.github.com>
@TobiasWrigstad
Fixing linting complaints
76c9c40
@TobiasWrigstad
Fixing broken PEP reference
d9e77b9
@TobiasWrigstad
Added newlines to svg files
88d5fdc
@hugovk
Merge branch 'main' into pep795
b631f15
@hugovk
Copy link
Member

hugovk commented Dec 19, 2025 •
edited
Loading

(I've resolved the conflict)

@mjp41 Please could you sign the CLA? See here.

@mjp41
Copy link

mjp41 commented Dec 19, 2025

(I've resolved the conflict)

@mjp41 Please could you sign the CLA? See here.

Done.

hugovk
hugovk reviewed Dec 19, 2025
View reviewed changes
hugovk
hugovk reviewed Dec 19, 2025
View reviewed changes
TobiasWrigstad and others added 6 commits December 19, 2025 17:21
@TobiasWrigstad @hugovk
Apply suggestions from code review
d632682 
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
@TobiasWrigstad @hugovk
Update peps/pep-0795.rst
1fa6870 
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
@TobiasWrigstad
Added copyright
77d1c1a
@TobiasWrigstad
Resolved a fixme
be2fb37
@TobiasWrigstad
Fixing two minor issues in code listings for escape hatches
51f43b7 
Thanks to Cornelius Krupp for pointing these out.
@TobiasWrigstad
Added a note about mutable types of named tuples
e069316 
As pointed out by Cornelius Krupp, types created
by the namedtuple constructor are mutable.
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Reviewers

@mdboom mdboom mdboom left review comments

@JelleZijlstra JelleZijlstra JelleZijlstra left review comments

@hugovk hugovk hugovk left review comments

@AA-Turner AA-Turner AA-Turner left review comments

Assignees

No one assigned

Labels

new-pep A new draft PEP submitted for initial review

Projects

None yet

Milestone

No milestone

Development

Successfully merging this pull request may close these issues.

6 participants

@TobiasWrigstad @AA-Turner @hugovk @mjp41 @mdboom @JelleZijlstra