[R] scope of variables in R

[Wacek Kusnierczyk]

Wacek Kusnierczyk wrote:
>
> this is where multiple assignment might be your friend:
>
>     source('http://miscell.googlecode.com/svn/rvalues/rvalues.r')
>     c(foo, bar, gee) := local({
>         shared = 0
>         foo = function() shared <<- 0
>         bar = function(bar) shared <<- bar
>         gee = function() print(shared)
>         c(foo, bar, gee) })
>   

... and of course, the functions do not need to be named within local,
unless recursion, for example, is used:

    source('http://miscell.googlecode.com/svn/rvalues/rvalues.r')
    c(reset, set, get) := local({
        shared = 0
        c(  function() shared <<- 0, 
	    function(bar) shared <<- bar, 
            function() print(shared) ) })


the ugly <<- is used here, but always with reference to a variable found
in the enclosing local scope, so the risk of messing with other
variables in outer scopes is minimal.

vQ