# Pylint — Comprehensive Static Code Analyzer for Python

> Pylint is a static analysis tool that checks Python code for errors, enforces coding standards, detects code smells, and provides refactoring suggestions with a configurable scoring system.

## Install

Save in your project root:

# Pylint — Comprehensive Static Code Analyzer for Python

## Quick Use
```bash
pip install pylint
pylint src/
```

## Introduction
Pylint is one of the oldest and most thorough Python static analysis tools. It checks for coding errors, enforces PEP 8 style conventions, detects code smells, and scores your code on a 0-10 scale. Its extensive checker system covers everything from unused imports to complex cyclomatic complexity.

## What Pylint Does
- Detects actual errors like undefined variables, wrong argument counts, and import failures
- Enforces coding standards based on PEP 8 with configurable rules
- Identifies code smells such as duplicate code, too many branches, and long functions
- Provides a numerical code quality score that tracks improvement over time
- Generates reports with statistics on module complexity, dependencies, and raw metrics

## Architecture Overview
Pylint parses Python source into an AST using the astroid library, which provides enhanced type inference beyond the standard ast module. Each checker is a visitor that walks the AST and emits messages when it detects violations. Checkers are organized into categories: convention, refactor, warning, error, and fatal. The message system supports fine-grained enable/disable controls at the file, block, or line level.

## Self-Hosting & Configuration
- Install with `pip install pylint` and run against any Python project
- Generate a starter config with `pylint --generate-rcfile > .pylintrc`
- Configure via `.pylintrc`, `pyproject.toml` under `[tool.pylint]`, or `setup.cfg`
- Disable specific checks with `--disable=C0114,R0903` or inline `# pylint: disable=` comments
- Set `--jobs=0` to use all CPU cores for parallel analysis of multiple modules

## Key Features
- Over 200 built-in checks covering errors, style, refactoring, and design issues
- The astroid engine provides deep type inference for accurate cross-module analysis
- Plugin system allows writing custom checkers for project-specific rules
- Editor integrations provide real-time feedback in VS Code, PyCharm, and Vim
- Score tracking helps teams measure code quality improvements over time

## Comparison with Similar Tools
- **Ruff** — much faster (Rust-based) but covers fewer checker categories
- **Flake8** — lighter and faster but less thorough on type inference and design checks
- **mypy** — type checker only, does not check style or code smells
- **Pyright** — focused on type checking with faster performance, not a general linter
- **Bandit** — security-focused scanner, not a general code quality tool

## FAQ
**Q: Is Pylint too slow for large projects?**
A: Pylint is slower than Ruff or Flake8 because it performs deeper analysis. Use `--jobs=0` for parallel execution and `--load-plugins` selectively to improve speed. Many teams run Ruff for fast feedback and Pylint in CI for thorough checks.

**Q: How do I use Pylint with pre-commit?**
A: Add the `pylint` mirror to your `.pre-commit-config.yaml`. For projects with dependencies, use `local` hooks that run in the project virtualenv to ensure accurate import checking.

**Q: Can Pylint check type annotations?**
A: Pylint performs some type-related checks but is not a full type checker. Pair it with mypy or Pyright for comprehensive type analysis.

**Q: What does the Pylint score mean?**
A: Pylint scores code from 0 to 10 based on the ratio of detected issues to lines of code. A score of 10 means no issues were found. The score formula is configurable.

## Sources
- https://github.com/pylint-dev/pylint
- https://pylint.readthedocs.io/en/stable/

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Source: https://tokrepo.com/en/workflows/549ff7b3-442c-11f1-9bc6-00163e2b0d79
Author: AI Open Source