pre-commit VS flake8

Today we are going to look at how to setup Black (a python code formatter) and pre-commit (a package for handling git hooks in python) to automatically format you code on commit.

# See https://pre-commit.com for more information # See https://pre-commit.com/hooks.html for more hooks repos: - repo: https://github.com/pre-commit/pre-commit-hooks rev: v3.2.0 hooks: - id: trailing-whitespace - id: end-of-file-fixer - id: check-yaml - id: check-toml - id: check-added-large-files - repo: local hooks: - id: tox lint name: tox-validation entry: pdm run tox -e test,lint language: system files: ^src\/.+py$|pyproject.toml|^tests\/.+py$ types_or: [python, toml] pass_filenames: false - id: tox docs name: tox-docs language: system entry: pdm run tox -e docs types_or: [python, rst, toml] files: ^src\/.+py$|pyproject.toml|^docs\/ pass_filenames: false - repo: https://github.com/pdm-project/pdm rev: 2.10.4 # a PDM release exposing the hook hooks: - id: pdm-lock-check - repo: https://github.com/jumanjihouse/pre-commit-hooks rev: 3.0.0 hooks: - id: markdownlint

Pre-commit hooks act as the first line of defense in maintaining code quality, seamlessly integrating with linters and code formatters. They automatically execute these tools each time a developer tries to commit code to the repository, ensuring the code adheres to the project's standards. If the hooks detect issues, the commit is paused until the issues are resolved, guaranteeing that only code meeting quality standards makes it into the repository.

Pre-commit Hooks: Pre-commit is a tool that can be set up to enforce coding rules and standards before you commit your changes to your code repository. This ensures that you can't even check in (commit) code that doesn't meet your standards. This allows a code reviewer to focus on the architecture of a change while not wasting time with trivial style nitpicks.

Ah, fair enough!

On my team we use pre-commit[0] a lot. I guess I would define the history to be something like "has this commit ever been run through our pre-commit hooks?". If you rewrite history, you'll (usually) produce commits that have not been through pre-commit (and they've therefore dodged a lot of static checks that might catch code that wasn't working, at that point in time). That gives some manner of objectivity to the "history", although it does depend on each user having their pre-commit hooks activated in their local workspace.

[0]: https://pre-commit.com/

Pre-commit is a framework for managing and maintaining multi-language pre-commit hooks. It supports hooks for various programming languages. Using this framework, you only have to specify a list of hooks you want to run before every commit, and pre-commit handles the installation and execution of those hooks despite your project’s primary language.

You can learn more here: pre-commit.com

Note this includes support for pre-commit.

As a nice next step, you could also add mypy to check your type hints are consistent, and automate running all this via pre-commit hooks set up with… pre-commit.

repos: - repo: https://github.com/pre-commit/pre-commit-hooks rev: v4.3.0 hooks: - id: trailing-whitespace - id: check-merge-conflict - id: check-yaml args: [--unsafe] - id: check-json - id: detect-private-key - id: end-of-file-fixer - repo: https://github.com/timothycrosley/isort rev: 5.10.1 hooks: - id: isort - repo: https://github.com/psf/black rev: 22.8.0 hooks: - id: black - repo: https://gitlab.com/pycqa/flake8 rev: 3.9.2 hooks: - id: flake8 - repo: https://github.com/pre-commit/mirrors-mypy rev: v0.971 hooks: - id: mypy args: [ --warn-unused-configs, --ignore-missing-imports, --disallow-untyped-defs, --follow-imports=silent, --install-types, --non-interactive ]

I just ran `pre-commit autoupdate`. It's asking for a username for https://gitlab.com/pycqa/flake8. :-(

Flake8 plugin for a smart line length validation.

repo: https://gitlab.com/pycqa/flake8 rev: 3.9.2 hooks:

Flake8 plugin that runs PyLint.

$ pre-commit install pre-commit installed at .git/hooks/pre-commit $ git add .pre-commit-config.yaml $ git commit -m "Add pre-commit config" [INFO] Initializing environment for https://github.com/pre-commit/pre-commit-hooks. [INFO] Initializing environment for https://gitlab.com/pycqa/flake8. [INFO] Initializing environment for https://github.com/pycqa/isort. [INFO] Initializing environment for https://github.com/python/black. [INFO] Installing environment for https://github.com/pre-commit/pre-commit-hooks. [INFO] Once installed this environment will be reused. [INFO] This may take a few minutes... [INFO] Installing environment for https://gitlab.com/pycqa/flake8. [INFO] Once installed this environment will be reused. [INFO] This may take a few minutes... [INFO] Installing environment for https://github.com/pycqa/isort. [INFO] Once installed this environment will be reused. [INFO] This may take a few minutes... [INFO] Installing environment for https://github.com/python/black. [INFO] Once installed this environment will be reused. [INFO] This may take a few minutes... Trim Trailing Whitespace.................................................Passed Check Yaml...............................................................Passed Check for merge conflicts................................................Passed Debug Statements (Python)............................(no files to check)Skipped Check for added large files..............................................Passed Fix requirements.txt.................................(no files to check)Skipped Check django project for potential problems..........(no files to check)Skipped Check django project for missing migrations..........(no files to check)Skipped flake8...............................................(no files to check)Skipped isort................................................(no files to check)Skipped black................................................(no files to check)Skipped

If you're looking for just good automated error checking, I personally use a bunch of flake8 plugins via pre-commit hooks: flake8-bugbear, flake8-builtins, flake8-bandit, etc. You can find a bunch of sites that give recommended plugins and you just need to pick which ones you care about :)

flake8 is Python style checker based on PEP8(Python Enhance Proposal 8). black is a good code formatter. But some items such as Documentation String, black is not provided the check option. flake8 not only helps for lack of black but also can be easily applied with black.