Controlling the order of useDynLib lines in NAMESPACE with roxygen2

Question

I am working on a R package that uses an external 3rd party dll to load data. I have written wrapper functions to that external dll that I can call with .C()

Assume that my package is called mypackage and the external is called xternal.dll . It seems that to load the mypackage.dll that is generated during compilation it is necessary that external.dll is loaded first. I am using roxygen2 to manage the NAMESPACE file, and I have used the #' @useDynLib tags. Unfortunately when roxygen2 writes the NAMESPACE file it adds the useDynLib calls in the lexical order of the shared object being called like AZ, az.

Is there a way to control the order of the useDynLib in the namespace by roxygen2 ?

So far I have found the follwing solutions and neither of them seems to be particularly compelling:

• Renaming my package to be lexically ordered after the external dll.

• Managing the NAMESPACE file manually .

Example: The function foo.R:

#' @export
#' @useDynLib xternal
#' @useDynLib mypackage
foo <- function(){
  return(FALSE)
}

results in the NAMESPACE after calling devtools::document() :

# Generated by roxygen2: do not edit by hand

export(foo)
useDynLib(mypackage)
useDynLib(xternal)

The package would fail to load, however if I manually swap the two useDynLib lines the package installs and works fine.

Answer 1

After a very helpful hint received on GitHub : The solution is to use the @rawNamespace tag, that writes a verbatim line into the NAMESPACE file:

foo.R:

#' @export
#' @rawNamespace useDynLib(xternal); useDynLib(mypackage)
foo <- function(){
  return(FALSE)
}

results in a NAMESPACE file:

# Generated by roxygen2: do not edit by hand

export(foo)
useDynLib(xternal); useDynLib(mypackage)

and the shared objects are loaded in the correct order.