Comment by Insimwytim
4 hours ago
I feel like many people (and industry in general) complicate things unnecessary.
Stacked pull requests break large changes into small, reviewable pull requests.
That's how pull requests are supposed to be, no? If yours aren't that - you ought to rewrite them.
With stacks, you can independently review and check each pull request, then merge everything together in one click.
Why would I want to do that instead merging (and deploying/testing) separately, which gives me more reliability?
No more opening a single large pull request that takes forever to review, or splitting work across multiple branches you have to keep manually rebasing.
Well, it doesn't seem like a simplification over dreaded "manual rebasing". And the target branch still moves, doesn't it? So, how are you "saved" from rebasing?
It's like responsibility is shifted from the author to the tool. That has been tried before, and every time it seem to consistently produce a similarly shaped mess in a different area of a process, but with an added bonus of the tool's own problems and restrictions.
Here's a common flow where I find stacked PRs are useful:
- I want to build feature X
- Ah, but it would work better if I refactored the module first
- I refactor then build feature X
- There's then some additional (and optional) cleanup work
As a reviewer I wouldn't want to see all this in a single PR, and the changes depend on each other so I can't open multiple independent PRs. Manual rebasing is fine but navigating the GitHub UI is then annoying, I have to mentally keep track of where I am in the stack.
Those could just be individual commits on a branch. Why does it need to be a stacked PR? That concept really only exists within the interfaces of these kinds of tools.
They don't. But reviewing individual commits in the GitHub UI is hard.
A set of stacked PRs is exactly the same as a line of commits. The only difference is the UI, but the UI is the important bit here because lack of UI is what's stopping folk from doing that today.
Even when I've developed my changes as a stack of commits, I'll feed them to my team one commit (and one PR) at a time so they're easier to review — and I discovered that GitHub had turned on stacked commits UI because for one particular project I'd manually created a set of PRs in advance (with the right bases) and GitHub offered to create a stack out of them.
2 replies →
They could but they don't belong together. A PR should be about one thing. Refactoring one module for another's sake should be done in another PR. If not for reviewing, for revertability, and future debuggability.
I certainly don't want to see that in a one commit. A PR has one more more commits, though.
The commits in a PR are already a stack of patches, and so PRs are already "stacked" as they are.
If feature X depends on the refactoring (cannot be rebased on the un-refactored upstream), it's part of the change; you can't just merge the feature and not the refactoring.
If the two are separable that way then, sure, it makes sense to ask for them to be separate PRs.
I do that too. I do introduce changes in separate PRs. They could be related to the same problem and referenced accordingly.
Why? Is it a technical restriction? Tightly coupled architecture is not the best solution anyway.
A refactor and then a feature implemented on that refactor is tightly coupled by definition. It would not make sense to implement the feature and refactor independently, because you’d be wasting time implementing a feature that you would have to refactor again.
1 reply →
I also don't get it.
> With stacks, you can independently review and check each pull request, then merge everything together in one click.
Consider:
"With pull requests, you can independently review and check each commit inside the pull request, and then merge the entire pull request in one click."
Pull requests are stacked commits. This does not have to recurse; you don't need stacked pull requests, not to mention stacked pull request stacks.
A commit can already contain changes to multiple files. In many cases, even a complex change can be just one commit. A sequence of multiple commits handles all the remaining cases.
Stacked PRs sound like a use case for someone who never wants a PR to be a container for multiple commits, such that if a unit of work is best done as three commits, they want them in separate PRs. Oh, but now they are not related together, the way a stack of commits is related under one PR, so we need a meta-PR to contain PRs or something.
This could be a consequence of commits being sort of second class citizens in the GitHub UI compared to PRs. If you want a commit to be treated as PR, on the same level, you must create a PR with nothing but that commit. So then, what would have been a single PR with four commits that you could merge with one click is now four PRs. Which you want to be able to merge them with one click.
> With pull requests, you can independently review and check each commit inside the pull request, and then merge the entire pull request in one click
Except you can’t really do that on GitHub, the “unit if review” is the PR so reviewing commits is adhoc, inconsistent, and awkward, and tracking their changes as they get fixed up is a pain. “Splatting” that as PRs is not the nicest way to do it green field, but it’s an evolution that makes sense in GitHub’s model.
Right; so maybe that's the thing to fix.
I don't mind rebasing, so that's not really an issue.
The problem I sometimes have is when I queue up 4 or 5 PRs in the afternoon and expect someone to take a look in the morning.
The diff of A into master looks OK, but then the diff of B looks like AB, and the diff of C looks like ABC - each PR has changes that will have already been merged once earlier PRs have been accepted.
My way around it was to raise E as a PR into D, raise D as a PR into C, etc. Then once approved, I change their destinations back to master for the actual merges.
It really confuses reviewers though, even though it's meant to make it so they only see the appropriate changes.