В Sun, 28 Apr 2024 15:15:06 +0000 Leo Mada <leo.m...@syonic.eu> пишет:
> This is why I intended to define a new method "proj.line3d" and > overload this method. But it seems that R interprets "line3d.numeric" > as a class - which originates probably from the "data,frame" class. It may help to call the original 'proj' function and your new 'proj.line3d' function "generics", because that's what most S3 literature calls these functions that you overload. This separates them from the "methods" 'proj.line3d.numeric' and 'proj.line3d.matrix' that can be said to "implement" or "overload" the generic. A concise but very readable guide to S3 and other built-in OOP systems in R can be found in Advanced R by Hadley Wickham: http://adv-r.had.co.nz/OO-essentials.html#s3 > How can I define a real method "proj.line3d"? In order to export an S3 generic and register methods for it from a package, you need the following directives in your NAMESPACE: export(proj.line3d) S3method(proj.line3d, numeric) # will use function proj.line3d.numeric S3method(proj.line3d, matrix) # similar <https://cran.r-project.org/doc/manuals/R-exts.html#Registering-S3-methods> > There might be some limitations from Roxygen as well (as I use it for > the package); but it might be easier to proceed, once I understand > how to do it in R. The roxygen2 documentation says that if there are multiple dots in the name of a function, you need to use the two-argument form of the @method keyword: @method proj.line3d numeric (untested). <https://roxygen2.r-lib.org/articles/rd-other.html#s3> > I thought that this solves the problem: > proj.line3d <- function(p, x, y, z, ...) > UseMethod("proj.line3d") Right. This is the definition of an S3 generic generic in R. As long as all the methods will also accept arguments (p, x, y, z, <maybe extra arguments here>, <dots>), all will be fine. > The other solution, as you pointed out, is more cumbersome; and it > needs 2 separate classes, so I would need to define "proj" as an S4 > class (as S3 does not handle 2 classes at once). Moreover, you still need an exported generic proj.line3d and registered methods for it to work. Inheritance does work in S3 (see NextMethod()), but it alone won't help you call proj.line3d.numeric() from proj() and 'numeric' x. -- Best regards, Ivan ______________________________________________ R-package-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-package-devel
