Unused arguments in R

Question

Is it possible to have a the software ignore the fact that there are unused arguments defined when a module is run?

For example, I have a module multiply(a,b), which returns the product of a and b. I will receive an error if I call the module like so:

multiply(a=20,b=30,c=10) 

Returning an error on this just seems a bit unnecessary, since the required inputs a and b have been specified. Is it possible to avoid this bad behaviour?

An easy solution would be just to stop specifying c, but that doesn't answer why R behaves like this. Is there another way to solve this?

Answer 1

Change the definition of multiply to take additional unknown arguments:

multiply <- function(a, b, ...) {   # Original code } 

Answer 2

The R.utils package has a function called doCall which is like do.call, but it does not return an error if unused arguments are passed.

multiply <- function(a, b) a * b  # these will fail multiply(a = 20, b = 30, c = 10) # Error in multiply(a = 20, b = 30, c = 10) : unused argument (c = 10) do.call(multiply, list(a = 20, b = 30, c = 10)) # Error in (function (a, b)  : unused argument (c = 10)  # R.utils::doCall will work R.utils::doCall(multiply, args = list(a = 20, b = 30, c = 10)) # [1] 600 # it also does not require the arguments to be passed as a list R.utils::doCall(multiply, a = 20, b = 30, c = 10) # [1] 600