You're quite right :-) But I think the polemic still holds, because I have
to add manual argument checking to all my methods, which has a cost in
lines of code. Indeed, few base R methods have chosen to do this. In
effect, the current setup encourages writing methods with "lenient"
argument specifications.
Thank you for the suggestion about ellipsis.
On Sun, 8 Mar 2020, 11:04 Gábor Csárdi, <csardi.ga...@gmail.com> wrote:
> You can add the ... argument to chop.default(), and then check that
> length(list(...)) is zero.
>
> Also, you might be interested in the ellipsis package.
>
> Gabor
>
> On Sun, Mar 8, 2020 at 10:56 AM David Hugh-Jones
> <davidhughjo...@gmail.com> wrote:
> >
> > Hi all,
> >
> > My package defines the following method and generic:
> >
> > chop <- function (x, ...) UseMethod("chop")
> >
> > chop.default <- function (x, breaks, labels, extend = NULL, drop = TRUE)
> {
> > ... }
> >
> > R CMD check then gives a warning:
> >
> > W checking S3 generic/method consistency (695ms)
> > chop:
> > function(x, ...)
> > chop.default:
> > function(x, breaks, labels, extend, drop)
> >
> > See section ‘Generic functions and methods’ in the ‘Writing R
> > Extensions’ manual.
> >
> > I can fix this by adding a ... argument to chop.default:
> >
> > chop.default <- function (x, breaks, labels, extend = NULL, drop =
> > TRUE, ...)
> >
> > But that makes the code less robust because e.g.
> >
> > chop(x, Breaks = 1:3)
> >
> > will no longer throw an error from the misspelled argument.
> >
> > Or I can write:
> >
> > chop(x, breaks, labels, extend, drop) UseMethod("chop")
> >
> > but this means I cannot use a different interface for a different method.
> >
> > This seems like a mistake. (That's the polemic.) Or am I missing a better
> > way? (That's the question.)
> >
> > David
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-package-devel@r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-package-devel
>
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