I wanted to write to understand what limitations there may be with making
set operations in base S3 generic functions. Are there any technical
limitations as to why this wouldn't be possible?
In writing a reply in R-Sig-Geo (1) today, I was reminded that `spdep`'s
set operations are not exported S3 methods—e.g. must use
spdep::union.nb()—because there is no generic declared in `base`.
I think the R ecosystem would benefit greatly from generics declared in
base for these methods. For example, the `generics` (2) package was
published in 2018 including S3 generics for set operations masking base.
`generics` has 189 reverse imports, I suspect quite a few of them are for
set operations.
Generics GitHub usage (duplicates ofc from forks)
- 353 results for importFrom(generics, union) (3)
- 361 results for importFrom(generics, intersect) (4)
- 355 results for importFrom(generics,setdiff) (5)
There are also a number of manual implementations of an S3 generic for set
ops that mask base. See the following search GitHub results
- 249 results for UseMethod("union") (6)
- 208 results for UseMethod("intersect") (7)
- 199 results for UseMethod("setdiff") (8)
references :
1. https://stat.ethz.ch/pipermail/r-sig-geo/2025-December/029582.html
2. https://cran.r-project.org/src/contrib/Archive/generics
3. https://github.com/search?q=importFrom%28generics%2Cunion%29+&type=code
4.
https://github.com/search?q=importFrom%28generics%2Cintersect%29+&type=code
5. https://github.com/search?q=importFrom%28generics%2Csetdiff%29+&type=code
6.
https://github.com/search?q=UseMethod%28%22union%22%29+language%3AR&type=code
7.
https://github.com/search?q=UseMethod%28%22intersect%22%29+language%3AR&type=code
8.
https://github.com/search?q=UseMethod%28%22setdiff%22%29+language%3AR&type=code
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