R Calling internal function from an exported function inside package

Question

I am creating an R package in RStudio. Say I have two functions fnbig() and fnsmall() in my package named foo. fnbig() is a function that must be accessible to the user using the package. fnsmall() is an internal function that must not accessible to the user but should be accessible inside of fnbig().

# package code
fnsmall <- function()
{
bla bla..
}

#' @export
fnbig <- function()
{
bla bla..
x <- fnsmall()
bla..
}

I have tried exporting fnsmall(). All works but it litters the NAMESPACE. I tried not exporting fnsmall(), but then it doesn't work inside fnbig() when using x <- fnsmall() or x <- foo::fnsmall(). Then I tried to use x <- foo:::fnsmall(), and it works. But I read that using :::is not recommended.

What is the best way to go about doing this? How do I call an internal function from an exported function?

Answer 1

But I read that using :::is not recommended.

I think you mention this based on the following statement in the manual for writing packages by R.

Using foo:::f instead of foo::f allows access to unexported objects. This is generally not recommended, as the semantics of unexported objects may be changed by the package author in routine maintenance.

The reason for this to be not recommended is that unexported functions have no documentation and as such have no guarantee from the side of the package author that they will keep doing what they do now.

However, since you are referring to your own unexported functions, you have full control of what is happening in those functions, so this objection is not as relevant.

Referring to it as foo:::fnsmall is therefore a good option.