The Lettergrade Rule

How do you know when a code review is “done”?

Let’s say you are the reviewer and see many small changes you’d like the author to make. At some point, you’ll agree that the introduced behavior changes are correct or at least harmless. The remaining comments are largely stylistic or involve misalignments in minor architectural choices.

The letter grade rule is a lens for determining if any remaining comments justify blocking the change. It goes something like this:

Does addressing your comment or doing what you suggest improve the reviewed code by at least half a letter grade?

Your comments are not worth blocking the review if the answer is no. Instead, leave them as suggestions that the author can take and do with it what they will. Then, move on with your life.

This route is respectful of the author’s time and yours. It also implicitly places some amount of trust and responsibility on the author, which is empowering.

You might now wonder what constitutes a half-a-letter-grade improvement.

Here’s a non-exhaustive list of things it is not:

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