Setting default values to a function/package R

Question

I've made a package with a function that asks for 3 values, like so:

example.foo("directory",vA1,vA2)

Now, I want to set a default value for both vA1 and vA2. I wrote the following piece of code, but I don't know why it ain't working

  if (!exists("vA1")) {
    vA1 = 2
  }

2 being the default value for vA1. When I run the package I get an "argument "vA1" missing, with no default". How do I set the default for this function? Thanks!

Answer 1

As Pascal points out, defaults to functions are provided by providing named arguments. For instance:

 fun <- function(x="Hello World") print(x)

 fun()
 [1] "Hello World"

 fun("and good bye")
 [1] "and good bye"