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Add --cache-dir command-line option - #5433

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cobaltt7 merged 5 commits into
psf:mainfrom
addu2612:feat-cache-dir-cli
Oct 5, 2026
Merged

Add --cache-dir command-line option#5433
cobaltt7 merged 5 commits into
psf:mainfrom
addu2612:feat-cache-dir-cli

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@addu2612

@addu2612 addu2612 commented Sep 24, 2026 •
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Description

Add a --cache-dir option so callers can configure Black cache storage without setting an environment variable. The command-line option takes precedence over BLACK_CACHE_DIR and works for both single-file and concurrent formatting.

The selected path now covers both formatting caches and blib2to3 grammar caches. Import-time grammar initialization is write-free until Click resolves the effective cache directory, so an explicit CLI path does not touch the environment/default cache.

Closes #5174

Testing

  • .venv/bin/python -m pytest tests/test_black.py -k cache -q (25 passed)
  • uvx pre-commit run --all-files (passed)
  • .venv/bin/python scripts/generate_schema.py (schema matches)
  • .venv/bin/python -m pytest tests/test_black.py -q --tb=short (174 passed, 1 skipped; 2 local Click color-output assertions failed because ANSI codes were stripped in this VPS environment)

Checklist - did you ...

  • Implement any code style changes under the --preview style, following the stability policy? (Not applicable; this does not change formatting style.)
  • Add an entry in CHANGES.md if necessary?
  • Add / update tests if necessary?
  • Add new / update outdated documentation?

@cobaltt7

cobaltt7 commented Sep 24, 2026 •
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https://github.com/addu1612/black/blob/9ce4319/src/black/nodes.py#L17 What is the impact of this line not being updated?

Also nit: please remove the blank line between changelog entires.

@github-actions

github-actions Bot commented Sep 24, 2026 •
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diff-shades results comparing this PR (2286fd0) to main (f4f6cd9):

--preview style: no changes

--stable style: no changes

What is this? | Workflow run | diff-shades documentation

@addu2612

addu2612 commented Sep 25, 2026

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Thanks for catching that. The line in nodes.py controls the blib2to3 grammar pickle cache, so leaving it unchanged meant --cache-dir only redirected the formatter cache.

I updated the branch so import-time grammar initialization does not read or write a cache before Click resolves the effective directory. The CLI then initializes grammar and formatter caches in the selected directory. I also added a subprocess regression test that pre-creates the BLACK_CACHE_DIR version directory and verifies an explicit --cache-dir leaves it untouched.

The changelog blank line is removed, and the branch is rebased onto current main.

cobaltt7
cobaltt7 reviewed Sep 30, 2026
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Comment thread src/black/__init__.py Resolved
cobaltt7
cobaltt7 reviewed Oct 1, 2026
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Comment thread src/black/cache.py Resolved
cobaltt7
cobaltt7 reviewed Oct 1, 2026
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Comment thread src/black/__init__.py Resolved
cobaltt7
cobaltt7 reviewed Oct 1, 2026
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Comment thread src/black/__init__.py Resolved
@addu2612
addu2612 force-pushed the feat-cache-dir-cli branch from 9bdd745 to 0ec6cc3 Compare October 1, 2026 18:36
cobaltt7
cobaltt7 reviewed Oct 3, 2026
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Comment thread src/black/cache.py Resolved
@addu2612
addu2612 force-pushed the feat-cache-dir-cli branch from 0ec6cc3 to c12b611 Compare October 4, 2026 04:15
@cobaltt7

cobaltt7 commented Oct 5, 2026

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Thanks!

@cobaltt7
cobaltt7 merged commit 1ed66a8 into psf:main Oct 5, 2026
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@kokokoXUY kokokoXUY mentioned this pull request Oct 5, 2026
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luketainton pushed a commit to luketainton/luke_instant-msg-api that referenced this pull request Oct 10, 2026
renovate[bot] @luketainton
chore(deps): update dependency black to <26.10.2,>=26.10.1 (#292)
a2ebfe2 
This PR contains the following updates:

| Package | Change | [Age](https://docs.renovatebot.com/merge-confidence/) | [Confidence](https://docs.renovatebot.com/merge-confidence/) |
|---|---|---|---|
| [black](https://github.com/psf/black) ([changelog](https://github.com/psf/black/blob/main/CHANGES.md)) | `<26.10.1,>=26.10.0` → `<26.10.2,>=26.10.1` | ![age](https://developer.mend.io/api/mc/badges/age/pypi/black/26.10.1?slim=true) | ![confidence](https://developer.mend.io/api/mc/badges/confidence/pypi/black/26.10.0/26.10.1?slim=true) |

---

### Release Notes

<details>
<summary>psf/black (black)</summary>

### [`v26.10.1`](https://github.com/psf/black/blob/HEAD/CHANGES.md#Version-26101)

[Compare Source](psf/black@26.10.0...26.10.1)

##### Highlights

This release fixes a security issue in Black's bundled GitHub Action. Repositories that
use the action are encouraged to update to the latest version of Black immediately. This
update is received automatically when using `psf/black@stable`, and is independent of
the version of Black installed by the action.

When the GitHub Action reads version specifiers from `tool.black.required-version`, it
now only accepts released versions of Black, as it already did for `black` requirements
in dependency lists. Other values, such as URL references, are now rejected. This issue
has been registered as `GHSA-cg8m-r9f2-5wm2`; a CVE identifier is pending.

##### Stable style

- Fix a long Jupyter notebook assignment magic (for example `x = !ls -la`) being wrapped
  in parentheses, which IPython can no longer run; such cells are now left unchanged
  ([#&#8203;5481](psf/black#5481))
- Keep repeated lines outside the selected `--line-ranges` unchanged ([#&#8203;5436](psf/black#5436))
- Fix `--line-ranges` formatting lines that follow a statement when formatting joins or
  re-indents that statement ([#&#8203;5484](psf/black#5484))
- Fix `--line-ranges` crashing with an internal error when an unselected statement has a
  `# fmt: skip` comment on the last line before a closing bracket ([#&#8203;5477](psf/black#5477))
- Prevent moving an encoding declaration (for example `# -*- coding: latin-1 -*-`) onto
  the first two lines of a file ([#&#8203;5487](psf/black#5487))
- Fix adding an extra trailing blank line inside a multi-line module docstring when its
  last line is near the line length limit ([#&#8203;5494](psf/black#5494))

##### Preview style

- Do not split short expressions on delimiters (such as binary operators, comparisons,
  or comprehensions) inside brackets when preceded by a standalone comment ([#&#8203;5455](psf/black#5455))
- Fix the unstable `string_processing` feature removing backslash-newline sequences from
  raw strings, which changed their value ([#&#8203;5482](psf/black#5482))
- Avoid adding unnecessary parentheses around unbreakable right-hand side expressions in
  assignments (such as annotated assignments or subscript targets) ([#&#8203;5473](psf/black#5473))
- Parenthesize expressions with parameter comments when they exceed the line length
  under `--preview` ([#&#8203;5442](psf/black#5442))
- Fix `wrap_long_dict_values_in_parens` dropping the parentheses around a right-hand
  side that contains a dictionary, leaving a line over the length limit ([#&#8203;5492](psf/black#5492))
- Fix the unstable `string_processing` feature adding a space after `*` or `**` in a PEP
  695 type parameter (`* Ts = ...`) when it splits a string in the parameter's default
  ([#&#8203;5504](psf/black#5504))
- Avoid unnecessary line splits of trailers (such as indexing/subscripts) when an
  earlier bracket split exceeds the line length only due to a trailing comment ([#&#8203;5498](psf/black#5498))

##### Configuration

- Add `--cache-dir` to configure the cache directory from the command line ([#&#8203;5433](psf/black#5433))
- Don't cache a file as formatted after formatting or checking it with `--line-ranges`,
  which made a later full `black --check` pass and `black` skip the unformatted lines
  ([#&#8203;5476](psf/black#5476))
- Respect a `.gitignore` that starts with a UTF-8 byte order mark. The mark became part
  of the first pattern, so that pattern never matched and Black formatted files that git
  ignores ([#&#8203;5497](psf/black#5497))

##### Performance

- Avoid quadratic runtime when splitting very long lines with many trailing bracket
  pairs (such as consecutive subscripts) ([#&#8203;5475](psf/black#5475))

##### Integrations

- Fix the GitHub Action crashing on dependency-group includes when `use_pyproject` is
  enabled ([#&#8203;5479](psf/black#5479))
- When the GitHub Action reads version specifiers from `tool.black.required-version`, it
  now only accepts released versions of Black, as it already did for `black`
  requirements in dependency lists. Other values, such as URL references, are now
  rejected. ([#&#8203;5510](psf/black#5510))

</details>

---

### Configuration

📅 **Schedule**: (UTC)

- Branch creation
  - At any time (no schedule defined)
- Automerge
  - At any time (no schedule defined)

🚦 **Automerge**: Enabled.

♻ **Rebasing**: Whenever PR is behind base branch, or you tick the rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update again.

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box

---

This PR has been generated by [Mend Renovate CLI](https://github.com/renovatebot/renovate).
<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiI0NC4xNDkuMCIsInVwZGF0ZWRJblZlciI6IjQ0LjE0OS4wIiwidGFyZ2V0QnJhbmNoIjoibWFpbiIsImxhYmVscyI6WyJ0eXBlL2RlcGVuZGVuY2llcyJdfQ==-->

Reviewed-on: https://git.tainton.uk/luke/instant-msg-api/pulls/292
Co-authored-by: renovate[bot] <renovate-bot@git.tainton.uk>
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Allow cache dir configuration via command-line argument

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@addu2612 @cobaltt7