[Rd] optional package dependency (enhances)

[Uwe Ligges]

On 20.01.2010 20:11, Allen S. Rout wrote:
> Ross Boylan<ross at biostat.ucsf.edu>  writes:
>
>> On Fri, 2010-01-15 at 10:48 +0000, Benilton Carvalho wrote:
>>> How about using:
>>>
>>> Enhances: Rmpi
>
>
> This unique local bestiary of dependencies is quite inconvenient for
> anyone trying to connect R with any other system of package
> management.  Below, I've included the rather byzantine scheme I've
> suggested in another forum for connecting R packages with RPM
> packages.  It made my head hurt to write it.
>
>
> I think that this spectrum of dependencies substantially complicates
> the work of anyone who wants to make R easily accessible to
> non-systems-administrator users.  I think the R community wants this
> accessibility work to be easy, not hard.
>
> IMO, there is a fairly small set of changes in R package ideology
> which could make a big improvement:
>
> 1) Everything necessary to load a library should be Required. (I
>     naively think this means Imports should also be Required, but I may
>     be misunderstanding some nuance of Imports)
>
> 2) Everything necessary to complete a CHECK should be Required.
>
>
> That's it.  In this way you now have only two classes of requirements:
>
> - 'Requires', which has essentially the same meaning as it does in
>     other dependency graph worlds.
>
> - Other stuff which R authors care about, but the systems
>    administrator need not understand.
>
>
>
> ----
>
> + The R community is much less sysadmin-y than other
>    language communities.  Several positions about correctness which
>    lots of admins take as Truth (i.e. dependency cycle == BAD) they
>    find to be more of an aesthetic call.  This is reasonable.
>
> + Different repositories in the R community have independant lives and
>    attitudes.  There is modest competition and grumbling between
>    maintainers associated with different repos.
>
> + Package dependencies cross repo boundaries; sticking with the
>    'Better' repositories just won't work, and discussion of these
>    variations tends to make R folks testy.
>
>   conclusion: The goal of evolving the R packages into a DAG is a
>   non-starter.
>
> + There are four classes of dependency in R-package land: Requires,
>    Imports, Suggests, and Enhances.


1. You probably mean "Depends" rather than "Requires".
2. You forgot "LinkingTo"



> + Requires and Imports are required to load the package. [1]
>
> + Suggests may be required to fully CMD CHECK the package [1]
>
> + The need for suggests at CMD CHECK can be deactivated by build
>    config file. [2]
>
> + Many of the dependency cycles can be avoided if we ignore Suggests
>    as an RPM dependency.
>
> Now, on to opinion:
>
> + We would like all official packages to have passed a full R CMD CHECK
>
> + We would like an absolute minimum of manual special case handling.
>    It may not be possible to make that amount zero.
>
> So: Here's my suggested procedure for building any single package,
> gangked from a message I sent to R-core:
>
> 1) Express binary package dependencies according to Depends and Imports.
>     I'll call this the 'narrow dependency graph'.
>
> 2) As part of the binary package build process, run CHECK
>     with R_CHECK_FORCE_SUGGESTS = false.
>
> I'll pull nomenclature out of my ear and call these "built" but not
> "checked".
>
> 3) Build all binary packages which are downstream according to all of
>     Depends, Imports, Suggests, and Extends.  I'll call this the 'broad
>     dependency graph'.
>
> 4) Install all the packages in the broad dependency graph.
>
> 5) for each package in the broad graph, run CHECK with
>     R_CHECK_FORCE_SUGGESTS=true.
>
> Then the affected packages are "checked".  Perhaps this can be noted
> with a signature.


All binary packages on CRAN are checked, we do not need a signature.

Recursive reverse dependencies are also checked after updates. Hence you 
do not need to worry at all. Be sure we did most of the work already.

Uwe Ligges



> .... Whew!
>
>
> ----
>
>
> - Allen S. Rout
>
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