[R] Text dependent on a variable in a R function

[Jim Lemon]

On 05/02/2010 10:00 PM, Duncan Murdoch wrote:
> ...
> I've seen this description a couple of times lately, and I think it's
> worth pointing out that it's misleading. The deparse(substitute(x))
> trick returns the *expression* that was passed to the argument x.
> Sometimes that's the name of a variable, but not always, and I think
> it's important to distinguish between names that need to be names, and
> expressions that can consist of nothing but a name, but can also be
> something else.
>
> So this function
>
> f <- function(x) deparse(substitute(x))
>
> will return "1 + 1" if you call it as f(1 + 1).
>
I'm very glad to know of this, but when I create a toy function like this:

playdep<-function(x) print(str(deparse(substitute(x))))
testvar<-1:5
playdep(testvar)
chr "testvar"
NULL

which is the same as I get with a literal string, and consistent with 
the help page for "deparse".

"Turn unevaluated expressions into character strings."

Unless I am mistaken, deparse just returns a string, whether or not it 
is the name of a variable.

Jim