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cpython-code-style

Development
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Use this skill when writing or modifying CPython code, preparing commits, or running style checks. Covers PEP 7 (C code) and PEP 8 (Python) compliance, pre-commit hooks, patchcheck validation, trailing whitespace rules, the no-type-annotations-in-Lib policy, and documentation formatting standards.

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I want to install this Agent Skill for this project in Codex.

Source SKILL.md: https://github.com/majiayu000/claude-skill-registry/blob/HEAD/skills/development/cpython-code-style/SKILL.md

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CPython Coding Style and Standards

Style Guidelines

Python code (Lib/ etc): Follow PEP 8. Be consistent with nearby code.

C code (Modules/, Objects/, Python/, Include/): Follow PEP 7. Be consistent with nearby code.

Critical Rules

NEVER leave trailing whitespace on any line. Pre-commit hooks will catch this.

ALWAYS preserve the final newline at the end of files.

NEVER add type annotations to Lib/ tree. Stdlib doesn't use inline annotations (maintained in typeshed separately). Annotations may be OK in Tools/ or test code if requested.

No autoformatting by default. Only use Doc/venv/bin/ruff format if explicitly requested.

Pre-Commit Workflow

Before committing, run from repo root:

# 1. Pre-commit hooks (checks whitespace, file endings, syntax)
pre-commit run --all-files

# 2. Patchcheck (MUST PASS - validates C/Python style, docs, whitespace)
make -C $BUILD_DIR patchcheck

# 3. If you modified Doc/, verify reStructuredText
make -C Doc check

# 4. Run relevant tests
$BUILT_PY -m test test_yourmodule -j $(nproc)

Documentation

  • Python docstrings: Follow PEP 257, document params/returns/exceptions
  • C comments: Follow PEP 7, document complex algorithms
  • reStructuredText (Doc/): Follow Sphinx/reST conventions, verify with make -C Doc check