Black: The Uncompromising Code Formatter

26.3.1 · active · verified Sat Mar 28

Black is an uncompromising Python code formatter that reformats code to improve readability. It is currently at version 26.3.1 and follows a regular release cadence, with new versions typically released every few months.

Warnings

breaking Black no longer supports running with Python 3.9 due to compatibility issues.
Fix: Upgrade to Python 3.10 or later.
gotcha Ensure that the 'tomli' package is installed, as it is required for parsing TOML configuration files.
Fix: Install 'tomli' using pip.

Install

pip install black Install Black

Imports

black
```
import black
```
No common mistakes identified

Quickstart

This script demonstrates how to use Black to format a Python file and a Python code string.

import os
import black

# Format a Python file
file_path = os.environ.get('FILE_PATH', 'example.py')
with open(file_path, 'r') as f:
    source_code = f.read()
formatted_code = black.format_file_contents(source_code, fast=False)
with open(file_path, 'w') as f:
    f.write(formatted_code)

# Format a Python string
code = 'def foo():\n    return 42'
formatted_code = black.format_str(code, mode=black.FileMode())
print(formatted_code)

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