using substitute to get argument name with

Question

I\'m trying to get the names of arguments in the global environment within a function. I know I can use substitute to get the name of named arguments, but I would like to b

Answer 1

I would go with

foo <- function(a, ...) {
print( n <- sapply(as.list(substitute(list(...)))[-1L], deparse) )
    n
}

Then

foo(x,y,z)
# [1] "y" "z"

---

Related question was previously on StackOverflow: How to use R's ellipsis feature when writing your own function? Worth reading.

---

Second solution, using match.call

foo <- function(a, ...) {
    sapply(match.call(expand.dots=TRUE)[-1], deparse)
}

Answer 2

The canonical idiom here is deparse(substitute(foo)), but the ... needs slightly different processing. Here is a modification that does what you want:

foo <- function(a, ...) {
    arg <- deparse(substitute(a))
    dots <- substitute(list(...))[-1]
    c(arg, sapply(dots, deparse))
}

x <- 1
y <- 2
z <- 3

> foo(x,y,z)
[1] "x" "y" "z"