[R] how to access an executing environment?

[Spencer Graves]

Hello:


       I'm writing code to modify a function, and I want to know how to 
access the executing environment of the function.  The example below 
extracts the body of a function and executes a single line but can't 
find "x1" in the function's executing environment.  How would you 
suggest fixing this?  Thanks, Spencer


fun1 <- function(x1=1){
   y <- x1
}
fun2 <- function(fun=fun1){
   bo <- body(fun)
   bo2 <- bo[[2]]
   z <- eval(bo2)
}
tst <- fun2()

Error in eval(expr, envir, enclos) : object 'x1' not found
>