PyFlakes

PyFlakes is a Python utility that checks for programming errors in Python code. It identifies unused imports and undefined names. Unlike linters that check for stylistic issues, PyFlakes focuses solely on detecting logical errors that are often indicative of bugs. Its primary goal is to catch simple, common mistakes that can lead to runtime errors or unexpected behavior.

The tool works by analyzing the abstract syntax tree (AST) of Python files. It keeps track of all names that are defined and all names that are used. If a name is imported but never used, or if a name is used but never defined, PyFlakes will report it as an error. This simple yet effective approach helps developers maintain cleaner and more robust code.

PyFlakes is often used in conjunction with other tools like pycodestyle (formerly PEP8) and pylint. While pycodestyle focuses on style, and pylint offers a more comprehensive analysis including complexity and potential code smells, PyFlakes provides a quick and focused check for a specific set of common errors. Its speed and simplicity make it a popular choice for automated code analysis in continuous integration pipelines and pre-commit hooks. The tool is available as a command-line utility and can be easily installed using pip.