[R-pkg-devel] A function in one of my package is now a method in base R

On 2024-08-02 10:35 a.m., Shu Fai Cheung wrote:

Hi All,

I have a function (not a method), sort_by(), in one of my packages. A
new method with the same name was introduced in the recent versions of
R (4.4.0 or 4.4.1, I forgot which one), resulting in potential
conflict in users' code.

Certainly, users can simply use pkg_name::function_name() to solve the
conflict. However, I would like to be consistent with base R and so I
am thinking about converting my function to a method for the class for
which my function is intended to work on (e.g, est_table).

However, my function has arguments different from those in the base R

sort_by():

Base R:

sort_by(x, y, ...)

My function:

sort_by(
   object,
   by = c("op", "lhs", "rhs"),
   op_priority = c("=~", "~", "~~", ":=", "~1", "|", "~*~"),
   number_rows = TRUE
)

If I write the function sort_by.est_table(), I would need to match the
argument names of the base R sort_by(). However, I think it is a bad
idea to rename the arguments in my function and it will break existing
code.

Any suggestions on how I should proceed? Is keeping my function as-is
a better option? Name conflict is not unusual across packages and so
users need to learn how to solve this problem anyway. Nevertheless, if
possible, I would like to solve the conflict internally such that
users do not need to do anything.

I think it's impossible to avoid some inconvenience to your users.

Here's what I'd suggest:

- Create a method for base::sort_by(), as you suggested you could.  Use
the generic's variable names for compatibility, but also add your extra
variable names as additional arguments, e.g.

  sort_by.est_table <- function(x, y, object,
    by = c("op", "lhs", "rhs"),
    op_priority = c("=~", "~", "~~", ":=", "~1", "|", "~*~"),
    number_rows = TRUE, ...) {

   # This test seems unlikely:  how would we have dispatch here if we
specified object explicitly?

   if (!missing(object) {
     if (!missing(x))
       stop("both x and object specified!")
     x <- object
   }

   # This one is more likely to do something:

   if (!missing(by)) {
     if (!missing(y))
       stop("both y and by specified!")
     y <- by
   }

   # Now proceed using x and y

   ...
}

- Create a separate function, e.g. sort_by_old() which is exactly
compatible with your old sort_by().  For users where the above doesn't
just work, they can switch to sort_by_old().

Duncan Murdoch