30
I often write functions that need to see other objects in my environment. For example:
> a <- 3
> b <- 3
> x <- 1:5
> fn1 <- function(x,a,b) a+b+x
> fn2 <- function(x) a+b+x
> fn1(x,a,b)
[1] 7 8 9 10 11
> fn2(x)
[1] 7 8 9 10 11
As expected, both these functions are identical because fn2 can "see" a and b when it executes. But whenever I start to take advantage of this, within about 30 minutes I end up calling the function without one of the necessary variables (e.g. a or b). If I don't take advantage of this, then I feel like I am passing around objects unnecessarily.
Is it better to be explicit about what a function requires? Or should this be taken care of via inline comments or other documentation of the function? Is there a better way?