If you are tired of maintaining your coding style, I have good news for you. Fortunately, there are developer tools that can automate and streamline mundane development tasks. In this blog, I'll show you how I integrated 2 static code analysis tools and a package manager for pre-commit hooks into Silke, my work-in-progress static site generator.

Black: The uncompromising Python code formatter

Black can help you automatically format your Python code that follows (most of) the style conventions in PEP 8. You can install this tool with Pip and Python 3.6.2+:

$ pip install black

After installation, Black should work without configuring anything else:

$ black .

Once Black is executed, it will tell you which files have been reformatted. When I ran it on Silkie, Black produced the following output:

reformatted silkie/silkie.py
All done! ✨ 🍰 ✨
1 file reformatted.

After testing Silkie, I was pleasantly amazed that Black didn't break my code. If you are still worried that Black may break your program by alternating your code, you can include the --diff flag when running it. That should allow Black to only suggest their changes.

VSCode Integration

If you use Visual Studio Code as your code editor, you can easily integrate Black into it. First, you need to create a settings.json file under .vscode folder if you haven't had it. Then, add these 2 lines to enable Black to reformat your Python code when you save your files:

{
    "python.formatting.provider": "black",
    "editor.formatOnSave": true,
}

Flake8: Python 3-in-one linter

A code linter should help developers identify potential errors and coding style violations in your code; and I think Flake8 can accomplish that. Flake8 combines PyFlakes, pycodestyle, and Ned Batchelder's McCabe script to enhance our Python code quality.

Setting it up is as easy as a one-line command:

pip install flake8

Once it's installed, you can run it on your project right away. However, you can save your time later by specifying which files and/or directories Flake8 should exclude from its scan. In order to do that:

1. Create a tox.ini file in your root directory.
2. Specify the excluded files/folders separated by commas. Take my project as an example:

[flake8]
exclude =
    # Version control directory
    .git,
    # GitHub configuration directory
    .github
    # Python compiled bytecode 
    __pycache__,
    # Python third-party libraries & packages
    lib,
    # Python scripts & binary files
    bin,
    # Build directory
    dist,

Then, I ran Flake8 on my project:

$ flake8 .

By default, Flake8's style rules may have some conflicts with Black's. For instance, although Black already formatted my code, Flake8 would still bug me for having too many characters per line:

./silkie/silkie.py:37:80: E501 line too long (83 > 79 characters)
./silkie/silkie.py:43:80: E501 line too long (84 > 79 characters)
./silkie/silkie.py:52:80: E501 line too long (80 > 79 characters)
./silkie/silkie.py:76:80: E501 line too long (86 > 79 characters)
./silkie/silkie.py:80:80: E501 line too long (80 > 79 characters)
./silkie/silkie.py:104:80: E501 line too long (80 > 79 characters)
./silkie/silkie.py:149:80: E501 line too long (80 > 79 characters)
./silkie/silkie.py:157:80: E501 line too long (80 > 79 characters)
./silkie/silkie.py:159:80: E501 line too long (83 > 79 characters)
./silkie/silkie.py:199:80: E501 line too long (85 > 79 characters)
./silkie/silkie.py:210:80: E501 line too long (88 > 79 characters)

Moreover, Flake8 found a false positive error:

./silkie/silkie.py:159:56: E203 whitespace before ':'

Flake8 actually complained about the whitespace before a list slice:

To resolve those issues, I configured Flake8 in tox.ini file, located in the root directory, to ignore those false positive stylistic errors:

[flake8]
max-line-length = 88
ignore =
    # False positive whitespace before ':' on list slice.
    # See https://github.com/PyCQA/pycodestyle/issues/373 for details
    E203

VSCode Integration

Flake8 can integrated into Visual Studio Code by adding these lines to settings.json file under .vscode folder:

{
    "python.linting.flake8Enabled": true,
    "python.linting.enabled": true,
    "python.linting.flake8Args": ["--max-line-length=88"],
    ...
}

Pre-commit: Multi-language pre-commit hooks manager

If you don't want to manually run Black and Flake8 before committing your changes, you can automate it with pre-commit.

To install pre-commit, run this command:

$ pip install pre-commit

Once it's installed, you can set up pre-commit hooks by specifying them in the .pre-commit-config.yaml file. For example, this is how I added Black and Flake8 as pre-commit Git hook scripts to my project:

repos:
  - repo: https://github.com/psf/black
    rev: 21.10b0
    hooks:
      - id: black
  - repo: https://github.com/pycqa/flake8
    rev: 4.0.1
    hooks:
      - id: flake8

To run these tools before every git commit commands, you need to install the scripts with this command:

$ pre-commit install

After installation, Black and Flake8 should be executed before any modification is committed.

Conclusion

I initially thought integrating these tools into my project would take a lot of time, but it was actually really quick and straightforward. Thanks to the development teams behind Black & Flake8, my life as a developer has been much easier. I can't wait to try out other awesome tools!