Taming Ruff: Displaying Rule Numbers in VS Code Warnings for Python

Tired of cryptic warnings from Ruff in VS Code that leave you guessing? Unlocking the power of Ruff involves understanding how to effectively interpret its warnings, especially when dealing with a large codebase. This article dives into how to configure Ruff to display rule numbers directly in VS Code, significantly boosting your debugging efficiency and speeding up your Python development.

Why Show Ruff Rule Numbers?

• Precision Debugging: Instead of vague descriptions, seeing the exact rule number (e.g., C416) allows you to pinpoint the issue instantly.
• Faster Learning: Rule numbers link directly to Ruff's documentation, providing context and rationale behind each rule. This helps you understand why the code is flagged, improving your overall coding practices.
• Efficiently Ignoring Rules: If a warning is deemed superficial (PLW0603, INP001), identifying the rule number makes adding it to your ignore list in ruff.toml a breeze.

Method 1: Hover for Instant Rule Revelation

The most user-friendly approach leverages Ruff's VS Code extension:

1. Install the Ruff Extension: Ensure the official Ruff extension for VS Code is installed and active.
2. Enable Python Linting: VS Code typically enables Python linting by default. If not, verify that it's active in your VS Code settings.
3. Hover for Details: Place your cursor over the code underlined with a squiggly line (indicating a Ruff warning). A tooltip will appear, displaying the Ruff rule code (e.g., Ruff(C416)).
4. Click Through to Learn: The rule code is often hyperlinked; clicking it opens the official Ruff documentation page for that specific rule.
   • Configuration Tip: Confirm that "ruff.path" in your VS Code settings points to the correct Ruff executable within your virtual environment. ("ruff.path": ["<full path to ruff in my virtual environment>"])
   • pyproject.toml: Make sure your Ruff configuration resides in a properly formatted pyproject.toml file in your project root.

Method 2: The "Problems" Tab – A Comprehensive View

If hovering doesn't immediately reveal the rule number, the "Problems" tab offers a broader perspective:

1. Open the "Problems" Tab: Located at the bottom of your VS Code window.
2. Examine the List: This panel displays all detected warnings and errors in your project.
3. Rule Numbers Displayed: You should find the Ruff rule numbers listed alongside each warning description.

Long-Tail Keywords covered:

• Python Ruff VS Code Integration
• Configuring Ruff in VS Code

Displaying Ruff rule numbers transforms cryptic warnings into actionable insights, improving your Python development workflow within VS Code. By understanding these methods, you and your team can become more productive and write higher-quality code.