Exporting s3 methods from namespace

[pepijn-devries]

Hi,

Thanks for all your work on this great package.

Many of the stars S3 methods are not exported in the NAMESPACE file. Consequently, when I'm developing a package that imports from stars, and call a generic like as.data.frame on a stars object, I get:

Error in UseMethod("as.data.frame") : 
  no applicable method for 'as.data.frame' applied to an object of class "stars"

Alternatively, importing the s3 method as.data.frame.stars or calling stars:::as.data.frame.stars won't work either as these function are not exported by stars. I guess my issue is related to issues https://github.com/r-spatial/stars/issues/504 and https://github.com/r-spatial/stars/issues/622. The difference is that I can't load the package with library when developing a package.

Is it possible to export these functions, or is there a reason not to?

Thanks for considering.

[edzer]

I see

$ grep as.data.frame NAMESPACE 
S3method(as.data.frame,dimensions)
S3method(as.data.frame,stars)
S3method(as.data.frame,stars_proxy)

[pepijn-devries]

Thanks for the quick response. Yes, I did see those, but those statements do not export the specific functions. Apparently, it's a bit of a hassle to get s3 methods of other packages into a different namespace.

I ended up using https://vctrs.r-lib.org/reference/s3_register.html and added this to my code:

.onLoad <- function(...) {
  s3_register("stars::as.data.frame", "stars")
}

That seemed to have done the trick...

[pepijn-devries]

Nope, I was too quick with my response. The code above won't build. Again, because as.data.frame.stars is not exported from stars. I did get it working by preceding the call to as.data.frame with:

requireNamespace("stars", quietly = TRUE)

Sometimes the solution can be so easy 😄 /