How to do merge conflict resolution?

[eWert-Online]

Hi,

When I am merging tree A and tree B and both have the same value modified, it results in a conflict.
Is there a way for me to say: In case of a conflict prefer B, but only in this one scenario?

So basically my question is: Is there a way to have custom merge functions for some cases or give context (prefer a or b) to the merge function?

[zshipko]

You can define a custom merge function for your Contents type using the operations in Irmin.Merge. It should just be a matter of overriding the merge value in your existing contents module.

Irmin.Merge.like could be used to modify an existing merge implementation.

[eWert-Online]

Thanks for the reply 🙂
I know, that I can create a custom merge function in my Contents definition.
My problem is, that I need a different behavior of the conflict resolution in different parts of my application.

For example: When I merge (as in the traditional git merge), I want to catch and report conflicts to my user. When I rebase a branch, I want the incoming (replayed) commits to always win.

So I need either different merge functions, or the ability to give some "context" to the merge function. But I guess this is currently just not possible and would need to be implemented

... or is there anything in irmin speaking against having multiple / different merge behaviors in an application?

[zshipko]

Ah yeah, right now that kind of conflict resolution would be something you implement in your application.

It seems like on the Irmin side it's not clear what reporting the conflicts look like or what resolution entails. I could imagine a ~on_conflict callback on Irmin.Store.merge that allows you to handle conflicts and continue or fail but I'm also not quite clear what the signature would look like or how to make sure it provides enough benefit over handling the merge results directly.

If you come up with something please share it!