Docstrings, comments & types

Writing documentation that lives in the code: docstring conventions from PEP 257, comments that help the next reader, and type hints from PEP 484 onwards.

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  Python Docstrings: PEP 257 Conventions, Formats and Tools

  How to write Python docstrings following PEP 257: one-line and multi-line docstrings, what to document for modules, classes and functions, the reST, Google and NumPy formats, doctest, and checking docstrings with ruff or pydocstyle.

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  Python Type Hints: From PEP 484 to Modern Syntax, with Style Rules

  A practical introduction to Python type hints: what annotations do and do not do at runtime, the syntax from PEP 484 to list[int], X | None and PEP 695 generics, how to format annotations, and how type checkers such as mypy use them.

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  Writing Useful Comments in Python: What PEP 8 Says and What Helps Readers

  How to write Python comments that help: PEP 8's rules for block and inline comments, explaining why rather than what, TODOs, commented-out code, tool directives such as noqa and type: ignore, and how comments differ from docstrings.