Question

In improving an rbind method, I’d like to extract the names of the objects passed to it so that I might generate unique IDs from those.

I’ve tried all.names(match.call()) but that just gives me:

[1] "rbind"         "deparse.level" "..1"           "..2" 

Generic example:

rbind.test <- function(...) {
  dots <- list(...)
  all.names(match.call())
}

t1 <- t2 <- ""
class(t1) <- class(t2) <- "test"
> rbind(t1,t2)
[1] "rbind"         "deparse.level" "..1"           "..2" 

Whereas I’d like to be able to retrieve c("t1","t2").

I’m aware that in general one cannot retrieve the names of objects passed to functions, but it seems like with … it might be possible, as substitute(...) returns t1 in the above example.

Answer 1

Using the guidance here How to use R's ellipsis feature when writing your own function?

eg substitute(list(...))

and combining with with as.character

rbind.test <- function(...) {
  .x <-  as.list(substitute(list(...)))[-1]
  as.character(.x)
 }

you can also use

rbind.test <- function(...){as.character(match.call(expand.dots = F)$...)}