Forcing specific data types as arguments to a function

Question

I was just wondering if there was a way to force a function to only accept certain data types, without having to check for it within the function; or, is this not possible b

Answer 1

I've found stopifnot() to be highly useful for these situations as well.

x <- function(n) { 
stopifnot(is.vector(n) && length(n)==1)
print(n)
}

The reason it is so useful is because it provides a pretty clear error message to the user if the condition is false.