>>>>> David Hugh-Jones <davidhughjo...@gmail.com> >>>>> on Tue, 14 Mar 2017 09:26:49 +0000 writes:
> Just out of interest, what would happen if I used the hacky solution of > simply exporting my own method like: > as.FlexTable <- function(x, ...) UseMethod("as.FlexTable") > I am fairly sure you will tell me that fire and brimstone will rain down… > But it sure seems simple compared to writing another package and getting > it on CRAN... no fire etc, but pretty close ;-) You will have two (internal) methods tables for as.FlexTable, one in ReporteRs, one in your package, and from a user point of view there's a deep abyss in functionality between working with require(ReporteRs); require(huxtable) and working with require(huxtable); require(ReporteRs) This is undesirable and error prone and can be resolved by correct imports as those mentioned. Martin > David > On Tue, 14 Mar 2017 at 09:06, Martin Maechler <maech...@stat.math.ethz.ch> > wrote: >> >>>>> David Hugh-Jones <davidhughjo...@gmail.com> >> >>>>> on Tue, 14 Mar 2017 02:46:35 +0000 writes: >> >>>>> David Hugh-Jones <davidhughjo...@gmail.com> >> >>>>> on Tue, 14 Mar 2017 02:46:35 +0000 writes: >> >> > Hi, >> > Cross-posted from SO: >> > >> http://stackoverflow.com/questions/42776058/extending-an-s3-generic-from-an-optional-package >> >> ((sent my answer there as well)) >> >> > I have a package which provides an as.FlexTable method for its >> objects, >> > extending the S3 generic from the ReporteRs package. So, my >> NAMESPACE file, >> > generated by roxygen, has lines: >> >> > importFrom(ReporteRs,as.FlexTable) >> > ... >> > S3method(as.FlexTable,huxtable) >> > ... >> > export(as.FlexTable) >> >> > I don't much want to put ReporteRs in Imports: in the DESCRIPTION >> file, >> > because it involves a big external dependency on Java. But, when I >> put it >> > into Suggests:, R CMD check gives me errors like "Namespace >> dependency not >> > required". >> >> > Is there anyway I can extend the generic without making a hard >> dependency? >> >> No. Importing is a hard dependency.. >> Some people do not import formally but use '<pkgNamespace>::<obj>' >> instead, *and* conditionalize their code on the availability of >> that namespace. >> I don't recommend that at all, and particularly not for >> extending a generic. >> >> I recommend you talk with the maintainer of 'ReporteRs': >> 1) You could use a common (yet-to-create) very small package say >> 'flexS3generics' >> which provides S3 generics (and S4 if ..) you want to use >> both, and then both you and her/him import from that mini package. >> You'd be both authors of that package. >> >> 2) If your package is much smaller (in its footprint, incl >> dependencies) than 'ReporteRs' she/he may agree to import the >> S3 generic from your package instead of the other way around. >> >> Both are clean solutions, >> and both need some time-coordination when releasing to CRAN, >> '1)' being easier: Once the 'flexS3generics' is released to >> CRAN, change (both) your package(s) to >> importFrom(flexS3generics,*) but these changes and CRAN >> submissions are then independent of each other. >> >> >> > Cheers, >> > David >> >> -- > Sent from Gmail Mobile > [[alternative HTML version deleted]] ______________________________________________ R-package-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-package-devel