R help - Mar 2009 - Please help me to understand environments

I want to write:

zap <- function(v) {
  if (exists(v)) {rm(v)}
}

But of course this doesn't work because the rm() acts on v which is
within zap() and doesn't affect the parent environment:
> x <- 1
> zap("x")
> x
[1] 1

How would I make this zap() function work?

-- 
Ajay Shah                                      http://www.mayin.org/ajayshah  
ajayshah at mayin.org                            
http://ajayshahblog.blogspot.com
<*(:-? - wizard who doesn't know the answer.

You might want to look at rm to see how that function handles the  
problem.

-- 
David Winsemius

On Mar 15, 2009, at 3:14 AM, Ajay Shah wrote:
> I want to write:
>
> zap <- function(v) {
>  if (exists(v)) {rm(v)}
> }
>
> But of course this doesn't work because the rm() acts on v which is
> within zap() and doesn't affect the parent environment:
>
>> x <- 1
>> zap("x")
>> x
> [1] 1
>
> How would I make this zap() function work?
>
> -- 
> Ajay Shah
David Winsemius, MD
Heritage Laboratories
West Hartford, CT