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

[Duncan Murdoch]

The problem with that is a call like

   sort_by( object = foo, by = bar )

wouldn't be dispatched to the est_table method when foo is an est_table 
object, it would give a "argument 'x' is missing" kind of error.  It 
would be fine for

  sort_by( foo, bar )

but would also mess up on

  sort_by( foo, bar, priority )

Duncan Murdoch

On 2024-08-03 7:13 a.m., Deepayan Sarkar wrote:
> I haven't thought about this carefully, but shouldn't this mostly work?
> 
>    sort_by.est_table <- function(x, y = c("op", "lhs", "rhs"),
>      object = x,
>      by = y,
>      op_priority = c("=~", "~", "~~", ":=", "~1", "|", "~*~"),
>      number_rows = TRUE, ...) 
> 
> <code unchanged>
> 
> }
> 
> -Deepayan
> 
> On Sat, 3 Aug 2024 at 00:13, Duncan Murdoch <murdoch.duncan using gmail.com 
> <mailto:murdoch.duncan using gmail.com>> wrote:
> 
>     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
> 
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