Commit Message Guidelines: Keeping Your Code History Clear

Table of contents

  1. Structure of a Good Commit Message:
  2. Benefits of Clear Commit Messages:
  3. Additional Tips:
  4. Checklist for Writing Effective Commit Messages

Writing clear and informative commit messages is essential for any developer working on a project. Effective messages act as a roadmap, helping everyone understand the “why” behind code changes. This not only improves collaboration but also makes maintaining and revisiting code in the future much easier.

Structure of a Good Commit Message:

A well-written commit message consists of two parts:

  1. A concise title (under 72 characters):

    • Written in the imperative mood (e.g., “Implemented user authentication” instead of “Implemented user authentication functionality”).
    • Briefly summarize the change and its purpose.
    • Avoid vague titles like “Changes to X” or “Fixed stuff”.

  2. Detailed message body (optional):

    • Provide context and additional details about the changes made.
    • Explain the motivation behind the change (e.g., fixing a bug, implementing a new feature).
    • Mention relevant issue references (e.g., “Fixes #123”).
    • Describe potential limitations or trade-offs of the implemented solution.
    • Use clear and concise language, avoiding unnecessary jargon.
    • Maintain readability with proper formatting and line breaks.

Example:

Refactored login flow for improved security (Fixes #145)

- Implemented secure password hashing using bcrypt.
- Added validation checks for username and password length.
- Removed unnecessary session handling logic.

This commit addresses security concerns raised in issue #145 by improving the login flow. Sensitive data is now protected with strong hashing, and user input is validated to prevent potential vulnerabilities.

Benefits of Clear Commit Messages:

  • Improved Collaboration: Clear messages allow team members to understand code changes quickly, facilitating effective collaboration.
  • Enhanced Code Maintainability: Informative messages make it easier to understand the codebase’s evolution and make future modifications.
  • Efficient Code Review: Detailed descriptions help reviewers grasp the changes and provide constructive feedback.
  • Future Reference: Well-written messages act as valuable documentation for revisiting code changes even years later.

Additional Tips:

  • Use consistent formatting: Consider adopting a team-wide style guide for commit messages to ensure uniformity.
  • Separate commits for logical changes: Break down large changes into smaller, more focused commits with clearer messages.
  • Focus on the impact: Explain how the changes affect system behavior or user experience.
  • Be specific, not generic: Use descriptive language that pinpoints the exact changes made.

Checklist for Writing Effective Commit Messages

Content and Clarity:

  • Clearly explain the motivation behind the change.
  • Describe the expected outcome of the change.
  • Explain the reasoning for choosing this approach over others.
  • Acknowledge any limitations or potential downsides.
  • Discuss the impact on other parts of the codebase or system.
  • Provide relevant background information or references.
  • Use clear and concise language that is easy to understand.

Structure and Formatting:

  • Organize the message into well-structured paragraphs.
  • Use line breaks to separate different points or sections.
  • Consider using bullet points to list key takeaways or changes.

Additional Considerations:

  • Split large commits into smaller, focused ones if necessary.
  • Use code comments for additional context.
  • Incorporate review feedback to improve your message.

By following this checklist, we can write commit messages that are informative, well-structured, and easy to understand.