A Starter for Python 2 Code Formatting with Black

Sun, 09 Feb 2025 00:00:00 +0000

Caution

Python 2.7 is the last major version in the 2.x series and . Please upgrade your Python if possible.

Some of the projects I work on still use Python 2.7. Installing Black for that case can take a little fiddling, so I’d like to show the steps that worked for me.

Note

, even for formatting Python 2 code.
The following assumes you have admin/root privileges and use pip as your package installer. Adjustments may be required to match your environment.

Table of Contents

Prerequisites: Python 3.6+ with a package installer

I am not going to cover how to install Python 3 or set up a package installer such as pip. You may need to search the web if your environment does not meet the prerequisites.

command -v python3
python3 -m pip -V

Install a specific Black version

python3 -m pip install 'black[python2]==21.12b0' click==8.0.4

V21.12b0 is the last Black version with support for formatting Python 2 code. As defined in , click >= 7.1.2 is a must.

click <= 8.0.4 is also required. Otherwise, you may encounter an error saying ImportError: cannot import name '_unicodefun' from 'click' when running Black.

The python2 extra for Black installs the optional dependency typed-ast, which . If there is no matching pre-built binary package for your environment, building it can fail with a Clang or GCC error. My suggestion is to remove [python2] as shown below. It generally works fine.

python3 -m pip install black==21.12b0 click==8.0.4

Verify installation

python3 -m black --version

Code Formatting |

A Starter for Python 2 Code Formatting with Black

Prerequisites: Python 3.6+ with a package installer

Install a specific Black version

Verify installation