Consider using *labelled* as backend

[thibautjombart]

It seems the package {labelled} is doing something very similar to our tagging system. We should consider using it as a backend. Some considerations:

• check it can actually replace current functionalities
• check if it adds useful functionalities
• check how many deps would be pulled in

[Bisaloo]

I learned today through @noamross that {labelled} is well-integrated with RStudio.

Digging through the code, it looks like it's not an integration specifically for {labelled}, but a generic feature for attr(, "label").

I think this looks quite nice so we should either switch to {labelled}, or for a base approach, replace attr(, "tag") by attr(, "label") in {linelist}.

[Bisaloo]

I've been doing a little bit more digging. The two approaches are actually much more different than what I said in my previous message:

• {labelled} set tags to the specific columns
• {linelist} set tags to the data.frame

There are benefits to both approaches. In particular:

• {labelled}:
  • it is harder to drop the attr() by accident
  • names<-(), rename() work out of the box without the need for a specific method
  • internal code can be greatly simplified in many cases
  • integrates well with RStudio UI
• {linelist}:
  • it is possible to retain tags even after columns are dropped but I don't believe this functionality is exposed to users
  • internal code can be greatly simplified in many cases (e.g., selecting specific tags can be done more easily, without having to loop through columns to extract their label)

Overall, it may be visible from my message that I prefer the attr() by column approach. However, I think it would require a major rewrite of the package and possibly cause some breaking changes, which is much more than what I had in mind when I started looking at this issue.

[Bisaloo]

Another alternative to mention in the README: https://github.com/karoliskoncevicius/annmatrix

[Bisaloo]

Interesting related blog post: https://www.pipinghotdata.com/posts/2022-09-13-the-case-for-variable-labels-in-r/