[R-pkg-devel] Question regarding listing base and recommended packages programmatically and efficiently

[Martin Maechler]

>>>>> Ivan Krylov 
>>>>>     on Thu, 12 Oct 2023 18:50:30 +0300 writes:

    > On Thu, 12 Oct 2023 11:32:24 -0400
    > Mikael Jagan <jaganmn2 using gmail.com> wrote:

    >> > mk <- file.path(R.home("share"), "make", "vars.mk")
    >> > pp <- sub("^.*= +", "", grep("^R_PKGS_RECOMMENDED",
    >> > readLines(mk), value = TRUE))
    >> > sort(strsplit(pp, " ")[[1L]])  
    >> [1] "KernSmooth" "MASS"       "Matrix"     "boot"       "class"
    >> [6] "cluster"    "codetools"  "foreign"    "lattice"    "mgcv"
    >> [11] "nlme"       "nnet"       "rpart"      "spatial" "survival"
    >> 
    >> I grepped around and did not find variables in any base namespace
    >> containing the names of these packages.  It wouldn't be too hard to
    >> define such variables when R is configured/built, but maybe there are
    >> "reasons" to not do that ... ?

    > tools:::.get_standard_package_names does that at package installation
    > time, but it's still not public API.

Within R-core, we have somewhat discussed this, and a few
minutes ago I committed a "public API" version of the above,
called
   standard_package_names()

to R-devel (svn rev 85329), and hence probably in next year's
April release of R.


    > A call to installed.packages() may take a long while because it has to
    > list files in every library (some of which can be large and/or
    > network-mounted) and parse each Meta/package.rds file, but at least
    > list.files() is faster than that.

The above is another issue that we've wanted to improve, as some
of you are aware,  notably thinking about caching the result
.. there has been work on this during the R Sprint @ Warwick a
couple of weeks ago,

 ==> https://github.com/r-devel/r-project-sprint-2023/issues/78

involving smart people and promising proposals (my personal view).

  > If I had to make a choice at this point, I would hard-code the list of
  > packages, but a better option may surface once we know what Tony needs
  > the package lists for.

  > -- 
  > Best regards,
  > Ivan


With thanks to the discussants here on R-devel,
and best regards,
Martin

--
Martin Maechler
ETH Zurich  and  R Core team