self detach

[romainfrancois]

It would be nice if nothing would detach itself. Not sure how to do that.

[romainfrancois]

I tried :

reg.finalizer( environment(), function(){
   detach( "package:nothing" )
})

in the .onLoad function, with no success. or perhaps the environment did not get gc'ed yet.

[wch]

This seems to unload self. You need to trick it into not doing this during installation, or installation will fail:

.onAttach <- function(libname, pkgname) {
  # Don't unload self when being installed - that will result in install error
  if (Sys.getenv("R_INSTALL_PKG") != "nothing") {
    unloadNamespace("nothing")
  }
}

[wch]

Actually, this code results in an error during library(nothing). But it works.

[wch]

Update: this seems to work without errors:

.onLoad <- function(libname, pkgname){
  if (Sys.getenv("R_INSTALL_PKG") == "nothing")
    return()

  pkgs <- setdiff(loadedNamespaces(), "base")
  while (length(pkgs) > 0) {
    for (pkg in pkgs) {
      try(unloadNamespace(pkg), silent = TRUE)
    }

    pkgs <- setdiff(loadedNamespaces(), "base")
  }
}

[leeper]

Perhaps an easier way to approach this is not loading the package at all, but instead having the package consist only of a single, non-exported function. Thus all the legwork is done with nothing:::nothing() instead of require(nothing). Just an idea.

[romainfrancois]

@leeper the essence of the package is that it gives meaning to the expression require(nothing). That's the only acceptable syntax ;)