[R-pkg-devel] Removing packages files

Thanks Henrik for confirming there is nothing similar currently.

Duncan: Letting the user choose when to remove the folder/data at will is easy.
I was trying to ensure that the system is clean after removing the package.
Thanks.

On Thu, 2 Jan 2025 at 22:42, Henrik Bengtsson
<henrik.bengtsson at gmail.com> wrote:

As a first step, this sounds like something for the 'tools' package,
e.g. tools::cleanup_R_user_dir() that wipes package subfolders of
packages no longer installed, or the specified package, iff given.
With that in place, one could argue for adding a 'cleanup' argument to
remove.packages() that use the former.

Agree, it would be neat if a package could clean up after itself when
uninstalled.

/Henrik

On Thu, Jan 2, 2025 at 1:37?PM Llu?s Revilla <lluis.revilla at gmail.com> wrote:

Dear Duncan,

Thank you for your answer. I checked again and made a mock package
that removes a file with .onDetach.
The file was not removed upon uninstalling the package.

Llu?s

On Thu, 2 Jan 2025 at 17:23, Duncan Murdoch <murdoch.duncan at gmail.com> wrote:

On 2025-01-02 9:55 a.m., Llu?s Revilla wrote:

Hi list,

I am developing a package that will download some data, and I'd like
to store it locally to not recalculate it often.
The CRAN policy requires tools::R_user_dir to be used and "the
contents are actively managed (including removing outdated material)"
or using TMPDIR but "such usage should be cleaned up".

When loading a package there is .onLoad or .onAttach to fill or check
those files and other settings required for a package. Is there
something for when a package is removed?

I found some related functions like .Last or reg.fnalizer and setHook
or packageEvent but they are about closing a session or don't have a
specific event for when uninstalling packages via (remove.packages). I
appreciate any feedback, thanks in advance.

Yes, those are described in section "1.5.3 Load hooks" of writing R
extensions:

"Packages can use a .onDetach or .Last.lib function (provided the latter
is exported from the namespace) when detach is called on the package. It
is called with a single argument, the full path to the installed
package. There is also a hook .onUnload which is called when the
namespace is unloaded (via a call to unloadNamespace, perhaps called by
detach(unload = TRUE)) with argument the full path to the installed
package?s directory. Functions .onUnload and .onDetach should be defined
in the namespace and not exported, but .Last.lib does need to be exported."

Duncan Murdoch