Global variables in R

I am poking into the manuals, I wanted to ask the community: How can we set global variables inside a function?

As Christian's answer with assign() shows, there is a way to assign in the global environment. A simpler, shorter (but not better ... stick with assign) way is to use the <<- operator, ie

    a <<- "new" 

inside the function.

I found a solution for how to set a global variable in a mailinglist posting via assign:

a <- "old"
test <- function () {
   assign("a", "new", envir = .GlobalEnv)
}
test()
a  # display the new value

What about .GlobalEnv$a <- "new" ? I saw this explicit way of creating a variable in a certain environment here: http://adv-r.had.co.nz/Environments.html. It seems shorter than using the assign() function.