Python – Page 86 – Sick Gaming

The Python programing language is often praised for its simple syntax. In fact the language recognizes that code is read much more often than it is written. Black is a tool that automatically formats your Python source code making it uniform and compliant to the PEP-8 style guide.

How to install Black on Fedora

Installing Black on Fedora is quite simple. Black is maintained in the official repositories.

$ sudo dnf install python3-black

Black is a command line tool and therefore it is run from the terminal.

$ black --help

Format your Python code with Black

Using Black to format a Python code base is straight forward.

$ black myfile.py
All done!    1 file left unchanged.
$ black path_to_my_python_project/
All done!   
165 files reformatted, 24 files left unchanged.

By default Black allows 88 characters per line, meaning that the code will be reformatted to fit within 88 characters per line. It is possible to change this to a custom value, for example :

$ black --line-length 100 my_python_file.py

This will set the line length to allow 100 characters.

Run Black as part of a CI pipeline

Black really shines when it is integrated with other tools, like a continuous integration pipeline.

The –check option allows to verify if any files need to be reformatted. This is useful to run as a CI test to ensure all your code is formatted in consistent manner.

$ black --check myfile.py
would reformat myfile.py
All done!   
1 file would be reformatted.

Integrate Black with your code editor

Running Black during the continuous integration tests is a great way to keep the code base correctly formatted. But developers really wants to forget about formatting and have the tool managing it for them.

Most of the popular code editors support Black. It allows developers to run the format tool every time a file is saved. The official documentation details the configuration needed for each editor.

Black is a must-have tool in the Python developer toolbox and is easily available on Fedora.

Install Python 3.8 on Fedora

If you have Fedora 29 or newer, you can install Python 3.8 from the official software repository with dnf:

$ sudo dnf install python38

As more alphas, betas and release candidates of Python 3.8 will be released, the Fedora package will receive updates. No need to compile your own development version of Python, just install it and have it up to date. New features will be added until the first beta.

Test your projects with Python 3.8

Run the python3.8 command to use Python 3.8 or create virtual environments with the builtin venv module, tox or with pipenv. For example:

$ git clone https://github.com/benjaminp/six.git
Cloning into 'six'...
$ cd six/
$ tox -e py38
py38 runtests: commands[0] | python -m pytest -rfsxX
================== test session starts ===================
platform linux -- Python 3.8.0a1, pytest-4.2.1, py-1.7.0, pluggy-0.8.1
collected 195 items

test_six.py ...................................... [ 19%]
.................................................. [ 45%]
.................................................. [ 70%]
..............................................s... [ 96%]
....... [100%]
========= 194 passed, 1 skipped in 0.25 seconds ==========
________________________ summary _________________________
py38: commands succeeded
congratulations

What’s new in Python 3.8

So far, only the first alpha was released, so more features will come. You can however already try out the new walrus operator:

$ python3.8
Python 3.8.0a1 (default, Feb 7 2019, 08:07:33)
[GCC 8.2.1 20181215 (Red Hat 8.2.1-6)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> while not (answer := input('Say something: ')):
... print("I don't like empty answers, try again...")
...
Say something:
I don't like empty answers, try again...
Say something: Fedora
>>>

Tag: Python

Make your Python code look good with Black on Fedora