[Rd] tools:: extracting pkg dependencies from DCF

[Gabriel Becker]

Hi Jan and Jan,

Can you explain a little more what exactly you want the non-recursive,
non-version aware dependencies from an individual package for?

Either way package_dependencies will do this for you* with a little
"aggressive convincing". It wants output from available.packages, but who
really cares what it wants? It's a function and we are people :)

> library(tools)
> db <- read.dcf("~/gabe/checkedout/rtables_clean/DESCRIPTION")
> package_dependencies("rtables", db, which = intersect(c("Depends",
"Suggests", "Imports", "LinkingTo"), colnames(db)))
$rtables
 [1] "methods"    "magrittr"   "formatters" "dplyr"      "tibble"
 [6] "tidyr"      "testthat"   "xml2"       "knitr"      "rmarkdown"
[11] "flextable"  "officer"    "stats"      "htmltools"  "grid"


The only gotcha that I see immediately is that "LinkingTo" isn't always
there (whereas it is with real output from available.packages). If you know
your package doesn't have that (or that it does) at call time , this
becomes a one-liner:

package_dependencies("rtables", db =
read.dcf("~/gabe/checkedout/rtables_clean/DESCRIPTION"), which =
c("Depends", "Suggests", "Imports"))
$rtables
 [1] "methods"    "magrittr"   "formatters" "dplyr"      "tibble"
 [6] "tidyr"      "testthat"   "xml2"       "knitr"      "rmarkdown"
[11] "flextable"  "officer"    "stats"      "htmltools"  "grid"

You can also trick it a slightly different way by giving it what it
actually wants

> tdir <- tempdir()
> file.copy("~/gabe/checkedout/rtables_clean/DESCRIPTION", file.path(tdir,
"PACKAGES"))
[1] TRUE
> avl <- available.packages(paste0("file://", tdir))
> library(tools)
> package_dependencies("rtables", avl)
$rtables
[1] "methods"    "magrittr"   "formatters" "stats"      "htmltools"
[6] "grid"

> package_dependencies("rtables", avl, which = "all")
$rtables
 [1] "methods"    "magrittr"   "formatters" "stats"      "htmltools"
 [6] "grid"       "dplyr"      "tibble"     "tidyr"      "testthat"
[11] "xml2"       "knitr"      "rmarkdown"  "flextable"  "officer"

So the only real benefits I see that we'd be picking up here is automatic
filtering by priority, and automatic extraction of the package name from
the DESCRIPTION file. I'm not sure either of those warrant a new exported
function that R-core has to maintain forever.

Best,
~G

* I haven't tested this across all OSes, but I dont' know of any reason it
wouldn't work generally.

On Fri, Oct 14, 2022 at 2:33 PM Jan Gorecki <j.gorecki using wit.edu.pl> wrote:

> Hello Jan,
>
> Thanks for confirming about many packages reinventing this missing
> functionality.
> packages.dcf was not meant handle versions. It just extracts names of
> dependencies... Yes, such a simple thing, yet missing in base R.
>
> Versions of packages can be controlled when setting up R pkgs repo. This is
> how I used to handle it. Making a CRAN subset mirror of fixed version pkgs.
> BTW. function for that is also included in mentioned branch. I am just not
> proposing it, to increase the chance of having at least this simple,
> missing, functionality merged.
>
> Best
> Jan
>
> On Fri, Oct 14, 2022, 15:14 Jan Netík <netikja using gmail.com> wrote:
>
> > Hello Jan,
> >
> > I have seen many packages that implemented dependencies "extraction" on
> > their own for internal purposes and today I was doing exactly that for
> > mine. It's not a big deal using read.dcf on DESCRIPTION. It was
> sufficient
> > for me, but I had to take care of some \n chars (the overall returned
> value
> > has some rough edges, in my opinion). However, the function from the
> branch
> > seems to not care about version requirements, which are crucial for me.
> > Maybe that is something to reconsider before merging.
> >
> > Best,
> > Jan
> >
> > pá 14. 10. 2022 v 2:27 odesílatel Jan Gorecki <j.gorecki using wit.edu.pl>
> > napsal:
> >
> >> Dear R devs,
> >>
> >> I would like to raise a request for a simple helper function.
> >> Utility function to extract package dependencies from DESCRIPTION file.
> >>
> >> I do think that tools package is better place, for such a fundamental
> >> functionality, than community packages.
> >>
> >> tools pkg seems perfect fit (having already great function
> >> write_PACKAGES).
> >>
> >> Functionality I am asking for is already in R svn repository since 2016,
> >> in
> >> a branch tools4pkgs. Function is called 'packages.dcf'.
> >> Another one 'repos.dcf' would be a good functional complementary to it.
> >>
> >> Those two simple helper functions really makes it easier for
> organizations
> >> to glue together usage of their own R packages repos and CRAN repo in a
> >> smooth way. That could possibly help to offload CRAN from new
> submissions.
> >>
> >> gh mirror link for easy preview:
> >>
> >>
> https://github.com/wch/r-source/blob/tools4pkgs/src/library/tools/R/packages.R#L419
> >>
> >> Regards
> >> Jan Gorecki
> >>
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> >>
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> >>
> >
>
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