It's not possible (?) to overload a generic with a named argument after the ellipsis

[cosi1]

Reproducible example:

## This works fine:
`metadata7<-` <- R7::new_generic("metadata7", signature = "x")

R7::method(`metadata7<-`, "Annotated7") <- function(x, ..., value) {
  if (!is.list(value)) {
    stop("replacement 'metadata' value must be a list")
  }
  if (!length(value)) {
    names(value) <- NULL # instead of character()
  }
  x@metadata <- value
  x
}
## This doesn't
`metadata7<-` <- R7::new_generic("metadata7", signature = c("x", "...", "value"))

R7::method(`metadata7<-`, "Annotated7") <- function(x, ..., value) {
  if (!is.list(value)) {
    stop("replacement 'metadata' value must be a list")
  }
  if (!length(value)) {
    names(value) <- NULL # instead of character()
  }
  x@metadata <- value
  x
}

[hadley]

What's the problem? This looks ok:

`metadata7<-` <- R7::new_generic("metadata7", signature = c("x", "...", "value"))

R7::method(`metadata7<-`, "Annotated7") <- function(x, ..., value) {
  if (!is.list(value)) {
    stop("replacement 'metadata' value must be a list")
  }
  if (!length(value)) {
    names(value) <- NULL # instead of character()
  }
  x@metadata <- value
  x
}

^{Created on 2021-10-22 by the reprex package (v2.0.1)}

[hadley]

Closing in favour of #85 where we'll make sure to fully support and test this pattern.