[R] Lazy evaluation in function call

[Thorn]

Hi everybody,

how is it possible to refer to an argument passed to a function in the 
function call? What I like to do, is something like

f <- function(x,y) x+y
f(2, x) # should give 4

The problem is of course that x is only known inside the function. Of course I 
could specify something like

f(z<-2,z)

but I'm just curious whether it is possible to use a fancy combination of 
eval, substitute or quote ;)

BR, thorn