On Thu, 5 Jan 2023 17:58:47 -0500 "Aaron A. King" <kin...@umich.edu> wrote:
> However, since the S3 dispatch system is not itself confused, I > suppose it must be the case that the S3 generic/method consistency > checker itself is confused. I wonder, how does the checker decide > when to throw a NOTE? Is it a simple pattern-matching system, > something like "If X.Y is exported, where X is a generic and Y is any > string and X.Y is not declared as an S3 method, then throw NOTE"? The aim of the check is a bit different: "if an S3 method for generic X and class Y exists, and the formal arguments of X.Y don't extend the formal arguments of X in a certain way, then throw a NOTE", but then something gets wrong about deciding whether X.Y is an S3 method, and once filter.mean is decided to be an S3 method, of course it doesn't match the formals of filter. This function is even a public API of the tools package, see ?tools::checkS3methods: https://github.com/r-devel/r-svn/blob/b57918fd104962415a752ea7db12dcf4f3f5219f/src/library/tools/R/QC.R#L2310-L2560 > When I follow your suggestion above, I get > > library(pomp) > dplyr::filter(structure(list(), class = 'traj')) > > Error in UseMethod("filter") : > no applicable method for 'filter' applied to an object of class "traj" Interesting. I wonder if there's are other remaining ways to confuse the S3 dispatch system into thinking your function is an S3 method that the check is supposed to guard against. For instance, the following is likely to work with your package: library(pomp) library(dplyr) identical(filter.traj, getS3method('filter', 'traj')) # as long as there's a visible 'filter' generic, getS3method will # locate filter.traj as the method ...despite the method lookup seems to (correctly) fail, as you've just demonstrated. But on older versions of R, this used to wrongly resolve the call: library(Ropj) read <- function(x, ...) UseMethod('read') identical(read.opj, getS3method('read','opj')) # works in R-devel # [1] TRUE read(structure(0, class = 'opj')) # calls read.opj in old R # Error in read_opj(file, encoding, tree) : # Expecting a single string value: [type=double; extent=1]. I'm afraid I'm out of my depth here. The old, wrong behaviour seems to match the R language definition <https://cran.r-project.org/doc/manuals/r-release/R-lang.html#Definition>. The current behaviour seems to do the right thing™ by letting the functions opt into being methods, but then getS3method() seems to contradict what actually gets called. Should we be fixing the documentation, the implementation, or the check? Can you try stepping through tools::checkS3methods('pomp') (or tools::checkS3methods(dir = 'path/to/source/directory')) to see where 'filter' appears in the list of generics and where the -- Best regards, Ivan ______________________________________________ R-package-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-package-devel
