r - Cast function argument as a character string?

Question

Super quick question...

How do you take a some particular function's (user-defined) argument and cast it as a character-string?

If for a simple example,

foo <- function(x) { ... }

I want to simply return x's object name. So,

foo(testing123)

returns "testing123" (and testing123 could just be some random numeric vector)

Apologies if this question has been asked before--searched, but couldn't find it! Thanks!!

Answer 1

foo <- function(x) deparse(substitute(x))