The three-dot question

Hi Michael,

Thanks for the reply.

On Mon, 2013-01-14 at 10:33 +0000, R. Michael Weylandt wrote:

Hi Feng,

I'm afraid I don't entirely understansd your question -- the `...`
construct only allows you to pass variable numbers of arguments, not
to have arbitrary access to the parent frames. You need to manually
extract "b" from the dots inside of testFun.

Also, it's quite frowned upon to put ##rm(list = ls())## in your
examples: it's the mailing list equivalent of asking a buddy to come
over to help you move and then punching him in the face when he tries
to lift your sofa.

The rm line just wants to declare there is no "b" in the global
environment. I did not mean people ought to try it. Also notice that
there is ">" in front of the rm. You won't get hurt if you just copy and
paste it. If it bites you, the mouse and keyboard did it:)

Cheers,

Feng

Cheers,
Michael


On Mon, Jan 14, 2013 at 10:21 AM, Feng Li <m at feng.li> wrote:

Dear all,

Why does not the three-dot accept arguments from the parent environment?
I am just confused with this error, can someone give me a hint?

rm(list=ls())
testFun <- function(a, ...)

+   {
+     if(a){
+         print(a)
+       }else
+       {
+         print(b)
+       }
+   }

myTask <- function(a)

+   {
+     b <- 3
+     testFun(a, b = b)
+   }

myTask(FALSE)

Error in print(b) : object 'b' not found


Thanks in advance!

Feng

--
Feng Li
Department of Statistics
Stockholm University
SE-106 91 Stockholm, Sweden
http://feng.li/