Differ does not perform row reloading if the changes is happening on same row. (macOS)

[martindufort]

Hey there,

I've started implementing Differ in our app to drive changes to our TableView.
As our app needs to support 10.15+, we cannot use the native DiffableSource implementation.

So using extendingDiff and patch, I realized that the current AppKit extension that applies the patch to the NSTableView is not using the reloadData(forRowIndexes: IndexSet, columnIndexes: IndexSet) when changes are applicable to a single row.

Here's our patch description:

EmailList DiffPatch [D(4), I(4,<Ocean.EmailListSource: 0x600002d323c0>)]

Why is this important?

By using Delete and Insert, if the selected row was 4, then it is automatically deselected.
This behavior, instead of using reloadDate(forRow...) makes for a pretty bad UX in our case.

Any suggestions on how to circumvent that? Thanks

[tonyarnold]

Hi Martin 👋 We should really coalesce that delete then insert of the same row into a reload. There's no workaround, but I'd warmly accept a PR 😄

I've not had much time to work on this library lately, so I won't make promises about when I might get to fixing this.

[martindufort]

Hey Tony,

I was able to quickly patch the Diff+AppKit.swift file to look for our use case and issue a reload.

However that patch is far away from being usable in the real world. I would need to further understand the internal mechanics of a Patch structure to provide a usable PR for you to review.

It's on my task list however, and like you 😃, it will take sometime to surface.
Let's keep this issue open until I come up with something.

Sounds good?

[tonyarnold]

Of course! I'd be happy for any contribution/help, whenever it can be given. Thanks for thinking about the problem.