[Rd] Importing packages in Depend

[Henrik Bengtsson]

On Thu, Sep 12, 2013 at 6:49 AM, Benjamin Hofner <benjamin.hofner at fau.de> wrote:
> Hi,
>
> I am currently preparing a new version of my package papeR. When I run R CMD
> check using the development version of R I get the following note:
>
> Package in Depends field not imported from: ‘nlme’, ‘lme4’, ‘survival’
>   These packages needs to imported from for the case when
>   this namespace is loaded but not attached.
>
> I now have problems to fix this issue. It is easy to get rid of two of the
> three package warnings by using
>
> import(lme4)
> import(survival)
>
> in my NAMESPACE. Yet, I cannot import nlme as I then get the following
> warnings:
>
> Warning: replacing previous import ‘VarCorr’ when loading ‘lme4’
> Warning: replacing previous import ‘lmList’ when loading ‘lme4’

This happens because 'lme4' re-exports the generic function VarCorr()
that 'nlme' already exports.  R considers this to be a conflict and
generates a warnings, which is detected by 'R CMD check'.   I've been
trying to argue that this warning is unnecessary/not correct because
in these cases, the two objects in conflict are actually the same
identical object.  You can see this by:

> nlme::VarCorr
function (x, sigma = 1, rdig = 3)
UseMethod("VarCorr")
<bytecode: 0x00000000111eb728>
<environment: namespace:nlme>

> lme4::VarCorr
function (x, sigma = 1, rdig = 3)
UseMethod("VarCorr")
<bytecode: 0x00000000111eb728>
<environment: namespace:nlme>

Note how they are both in the same namespace, i.e.

> identical(lme4::VarCorr, nlme::VarCorr)
[1] TRUE


I've submitted a patch for this 'Bug 15451 - PATCH:
namespaceImportFrom() not to warn when the identical object is
imported twice' on 2013-09-10
[https://bugs.r-project.org/bugzilla3/show_bug.cgi?id=15451].  The
tricky part is to convince R-core.

Otherwise, the only solution I know of is either to use importFrom():s
or to convince the author of 'lme4' to remove that re-export, which
may not be possible.

/Henrik

>
> I know that nlme is imported in lme4 but I cannot import both at the same
> time. Can anyone help me here? I do *not* want or can use importFrom as I
> rely on multiple functions and also rely on non-exported methods such as
> summary.lme().
>
> Thanks and all the best,
> Benjamin
>
>
>
> --
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