[Rd] Allowing S3 methods of rounding functions to take `...`

[Gabriel Becker]

Out of my naive curiosity, what arguments are you hoping a method for t()
will take?

I mean honestly an argument could be made that all S3 generics should take
.... I don't think its an overwhelmingly compelling one, but I d see some
merit to it given what an s3 generic is at its core.

~G

On Thu, Jan 28, 2021 at 5:27 PM Abby Spurdle <spurdle.a using gmail.com> wrote:

> That's a great suggestion Davis.
>
> While, we're on the topic...
> Could we have a "dots" argument in base::t, the transpose function?
>
>
> On Fri, Jan 29, 2021 at 4:48 AM Davis Vaughan <davis using rstudio.com> wrote:
> >
> > I should also say that I would be willing to attempt a patch for this, if
> > others agree that this would be useful.
> >
> > - Davis
> >
> > On Thu, Jan 28, 2021 at 9:14 AM Davis Vaughan <davis using rstudio.com> wrote:
> >
> > > Hi all,
> > >
> > > I would like to propose adding `...` to the signatures of the following
> > > rounding functions:
> > >
> > > - floor(x)
> > > - ceiling(x)
> > > - round(x, digits = 0)
> > > - And possibly signif(x, digits = 6)
> > >
> > > The purpose would be to allow S3 methods to add additional arguments as
> > > required.
> > >
> > > A few arguments in favor of this change:
> > >
> > > `trunc(x, ...)` already takes dots, which sets a precedent for the
> others
> > > to do so as well. It is documented in the same help file as the other
> > > rounding functions.
> > >
> > > Internally at the C level, a check is done to ensure that there is
> exactly
> > > 1 arg for floor() and ceiling(), and either 1 or 2 args for round().
> The
> > > actual names of those arguments are not checked, however, and I believe
> > > this is what allows `round.Date(x, ...)` and `round.POSIXt(x, unit)` to
> > > exist, solely because they have 2 arguments. It seems like this is a
> bit of
> > > a hack, since you couldn't create something similar for floor, like
> > > `floor.POSIXt(x, unit)` (not saying this should exist, it is just for
> > > argument's sake), because the 1 argument check would error on this. I
> think
> > > adding `...` to the signature of the generics would better support
> what is
> > > being done here.
> > >
> > > Additionally, I have a custom date-like S3 class of my own that I would
> > > like to write floor(), ceiling(), and round() methods for, and they
> would
> > > require passing additional arguments.
> > >
> > > If R core would like to make this change, they could probably tweak
> > > `do_trunc()` to be a bit more general, and use it for floor() and
> > > ceiling(), since it already allows `...`.
> > >
> > > A few references:
> > >
> > > Check for 1 arg in do_math1(), used by floor() and ceiling()
> > >
> > >
> https://github.com/wch/r-source/blob/fe82da3baf849fcd3cc7dbc31c6abc72b57aa083/src/main/arithmetic.c#L1270
> > >
> > > Check for 2 args in do_Math2(), used by round()
> > >
> > >
> https://github.com/wch/r-source/blob/fe82da3baf849fcd3cc7dbc31c6abc72b57aa083/src/main/arithmetic.c#L1655
> > >
> > > do_trunc() definition that allows `...`
> > >
> > >
> https://github.com/wch/r-source/blob/fe82da3baf849fcd3cc7dbc31c6abc72b57aa083/src/main/arithmetic.c#L1329-L1340
> > >
> > > - Davis
> > >
> >
> >         [[alternative HTML version deleted]]
> >
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