[R-pkg-devel] cross-ref possible ext.pkg's --not mentioned in DESCRIPTION file-- in non-code sections in .Rd files

[Martin Maechler]

>>>>> Andrew Simmons 
>>>>>     on Mon, 7 Nov 2022 12:19:48 -0500 writes:

    > Packages in Suggests and Enhances do not create a circular dependency, only
    > the packages in the Depends and Imports need to be installed at INSTALL and
    > loaded at load time. Packages in Suggests and Enhances are only needed at
    > check time, and even then it's more of a desire to be loaded than actually
    > needing to be loaded.

    > I would just put them in Suggests or Enhances

Thank you, Andrew.

'Enhances'  I think would be preferable.

Still, as Peter, I am not very happy about this NOTE.
Notably as I guess people will use (even) less \link{..} in
their R documentation (*).

... but yes, we can live with it, and I'm sure Peter will keep
his Rd files well maintained in spite ..

Martin


--
*) which is often lacking anyway, in my view
   because things like roxygen implicitly/indirectly suggest to
   many package authors that documentation is something you do as
   quickly and as shortly as possible..

    > On Mon, Nov 7, 2022, 11:10 Peter Ruckdeschel <peter.ruckdeschel using web.de>
    > wrote:

    >> Hi,
    >> 
    >> triggered by some new NOTEs uncovering infallacities in my packages on
    >> CRAN, I stumbled upon
    >> 
    >> Result: NOTE     Undeclared packages ‘distrMod’, ‘RobAStBase’ in Rd xrefs
    >> 
    >> which is issued in R-devel-linux-x86_64-fedora-clang (but not otherwise).
    >> 
    >> Digging into it, this comes from a text in a \seealso section where
    >> through something like
    >> 
    >> \code{\{link}[<ext.pkg>]{<generic>}
    >> 
    >> we want to link to a method provided in some extension package <ext.pkg>
    >> for a generic
    >> <generic> documented in Rd-file of the current package.
    >> 
    >> In this case, we intentionally do not have <ext.pkg> in any of the entries
    >> "Depends", "Suggests",
    >> "Imports", "Enhances" in the DESCRIPTION file, as <ext.pkg> is neither
    >> needed visible for the
    >> user, nor for the code in the current package nor for testing code nor for
    >> example code and vignettes
    >> of the current package, and because having it in "Suggests" would produce
    >> a circular dependence
    >> as <ext.pkg> has the current package in its "Imports" section.
    >> 
    >> Of course, in "Writing R extesions" we find that
    >> 
    >> "Packages referred to by these ‘other forms’ should be declared in the
    >> DESCRIPTION file, in
    >> the ‘Depends’, ‘Imports’, ‘Suggests’ or ‘Enhances’ fields. "
    >> 
    >> so I am aware that this is my fault, as I use these 'other forms'  without
    >> declaration in the DESCRIPTION file.
    >> Now I guess I could wrap my conditional cross-ref into some R-code,
    >> testing whether <ext.pkg> is available,
    >> i.e., something like
    >> 
    >> \Sexpr[eval=TRUE,stage=render,results=text]{if("<ext.pkg>" %in%
    >> installed.packages()[,1] )
    >> cat("\\code{\\{link}[<ext.pkg>]{<generic>}") else cat("<generic> from
    >> package \\pkg{<ext.pkg>})
    >> 
    >> and so produce the link only if <ext.pkg> is installed at rendering time,
    >> but I would guess such a
    >> conditional linkage would be something which could be of interest to a
    >> broader scope of R-package
    >> developers and hence could and should be implemented in a less cumbersome,
    >> and more
    >> efficient way.
    >> 
    >> Any suggestions welcome,
    >> best, Peter
    >> 
    >> --
    >> %******************************************************************
    >> % Prof. Dr. Peter Ruckdeschel
    >> % Institut fuer Mathematik, Fakultaet V - Mathematik und
    >> Naturwissenschaften
    >> % Carl von Ossietzky Universitaet Oldenburg,
    >> % Postfach 5634,  26111 Oldenburg
    >> % Office: Wechloy W1 02-227 Tel: +49 (0)441 798-3240  Fax: +49 (0)441
    >> 798-193240
    >> %peter.ruckdeschel using uni-oldenburg.de
    >> %http://www.uni-oldenburg.de/peter-ruckdeschel
    >> %******************************************************************
    >> 
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    >> 
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