Blog Engineering How patch files can transform how you review code
March 15, 2021
2 min read

How patch files can transform how you review code

We explain how to use patch files for better code review.


This post is adapted from a GitLab Unfiltered blog post written by me, David O'Regan. In part one of our series, we explain the importance of fairness and empathetic thinking in code reviews.

Patch files

Wanna know a git secret? Patch files are magic when it comes to code reviews. A patch is a text file whose contents are similar to Git diff but along with code it contains metadata about commits, for example, a patch file will include commit ID, date, commit message, etc. We can create a patch from commits and other people can apply them to their repository.

How to use a patch file

A patch file is useful for code review because it allows the reviewer to create an actionable piece of code that shares their thoughts with the MR author. The code author can then apply the suggestion directly to their merge request. Patch files foster collaboration because it essentially creates a paired programming session in the review process.

This lets other people check your changes in the git patch files for any corrections that need to be made before the changes truly go live. After everything has been checked and corrections made, the changes can be pushed to the main branch of the repository.

One of the better examples of a simple patch file in action comes from Denys Mishunov, staff frontend engineer on the Create team.

Index: app/assets/javascripts/projects/commits/components/author_select.vue
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP

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