Can `vec_math()` implement `round()` and `signif()`?

[davidchall]

Reading around this topic, it appears round() and signif() can either be implemented via the Math S3 group generic or the Math2 S4 group generic. {vctrs} implements the S3 generic via vec_math(): https://github.com/r-lib/vctrs/blob/faccc3aa6d8772a8cbc32b1d254b745685d3c4ff/R/type-vctr.R#L555-L558

However, the documented list of functions supported by vec_math() appears to be those supported by the Math S4 group generic (which excludes round() and signif()): https://github.com/r-lib/vctrs/blob/5eecfee07c6b231f29358b6883cee4c9e7f24576/R/numeric.R#L16-L22

Please can you clarify if vec_math() should be used to implement round() and signif()? Initial testing shows that it works, but I'm not sure if there are any caveats (e.g. how to pass additional arguments)?

[krlmlr]

I see round and signif mentioned in ?groupGeneric. Source location: https://github.com/r-devel/r-svn/blob/ecff5c591f8b1cfa80c0055c1c6da430481e804b/src/main/arithmetic.c#L1589-L1590 .

I suspect you'll be seeing the extra arguments in the ellipsis, does it work when you add them to the signature?

Perhaps we should add pointers to the documentation.