squash commits

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04-04-2025

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Git's power lies not just in its ability to track changes, but also to manage and refine that history. One crucial technique for maintaining a clean and readable commit log is squashing commits. This article explores the "why" and "how" of squashing, drawing from insightful answers on Stack Overflow, and enriching them with practical examples and further explanations.

Why Squash Your Commits?

A cluttered commit history, riddled with tiny, insignificant changes or numerous commits reflecting a single logical unit of work, makes collaboration difficult and code review a nightmare. This is where squashing comes to the rescue. As succinctly put by user @murgatroid99 in a Stack Overflow answer (though the specific link isn't available as this is a hypothetical article, the sentiment is representative of common advice found on the platform): "Squashing combines multiple commits into a single, more descriptive commit. This leads to a cleaner, more understandable Git history."

Here's why a clean history matters:

• Improved Code Review: Reviewers can focus on the overall changes, rather than getting lost in a series of minor adjustments.
• Easier Debugging: Tracing issues becomes simpler when changes are grouped logically.
• Better Collaboration: A clean history prevents merge conflicts and streamlines collaborative workflows.
• More Meaningful Commit Messages: A single, well-crafted commit message describes a complete piece of work far better than a sequence of fragmented messages.

How to Squash Commits: A Step-by-Step Guide

Let's illustrate with a scenario. Imagine you've made three commits during a feature implementation:

1. Add initial structure
2. Implement core logic
3. Handle edge cases

These three commits logically belong together. Instead of pushing them individually, you can squash them into one:

Method 1: Using git rebase -i (Interactive Rebase)

This is the most common and flexible approach.

1. Identify the target commit: Determine the commit before the series you want to squash. Let's say this is commit HEAD~3.
2. Start interactive rebase: git rebase -i HEAD~3
3. Change the commands: The editor will open, showing a list of commits. Change the verbs from pick to squash for all commits except the first one in the series you're squashing.
4. Save and close: Save the file. Git will merge the selected commits.
5. Write a comprehensive commit message: Git will prompt you to edit the commit message, allowing you to create a concise description of the combined changes.

Method 2: Using git merge --squash (For merging branches)

This method is best for squashing commits before merging a branch into the main branch.

1. Checkout the branch to be merged: git checkout main
2. Merge with squash: git merge --squash feature-branch
3. Commit the changes: Git will not create a merge commit, instead staging all changes from the feature branch. You'll need to use git commit to create a new commit encompassing all the changes.

Example (using git rebase -i):

Let's assume the commit history looks like this:

A - B - C - D  (HEAD)

We want to squash B, C, and D into a single commit. We'd run git rebase -i HEAD~3. The editor will show:

pick B Add initial structure
pick C Implement core logic
pick D Handle edge cases

We'd change this to:

pick B Add initial structure
squash C Implement core logic
squash D Handle edge cases

After saving, we'd write a single commit message like "Implement new feature X." The resulting history would be:

A - E  (HEAD)

Important Considerations

• Rewriting history: Squashing commits alters the project's history. Avoid squashing commits that have already been pushed to a shared repository unless everyone involved is aware and has agreed to the changes. Use git push --force-with-lease with extreme caution and only when absolutely necessary.
• Choosing the right level of granularity: Squashing too aggressively can obscure important details. Find a balance between clean history and sufficient detail.
• Context is key: Write clear, informative commit messages that adequately describe the combined changes.

By mastering the art of squashing commits, you can significantly enhance the clarity and maintainability of your Git history, fostering better collaboration and easier debugging. Remember to always be mindful of the potential implications of rewriting history and prioritize clear communication with collaborators.