[R-pkg-devel] Building my R package: issue when importing two functions with the same name

[Rainer M Krug]

Probably discussed already, but what is the difference between using “::” and “ImportFrom”? I usually use ImportFrom and “::” just to make clear, where the function is coming from - is this a problem?

Rainer


> On 7 Aug 2018, at 11:14, Uwe Ligges <ligges using statistik.tu-dortmund.de> wrote:
> 
> ... and even if you are importing from several packages, you should import selective via importFrom directoves.
> 
> If you need two functions with identical names, import at most one of them and rather use pkg::foo syntax to access them.
> 
> Best,
> Uwe Ligges
> 
> 
> 
> 
> 
> On 07.08.2018 10:14, Iñaki Úcar wrote:
>> El mar., 7 ago. 2018 a las 9:32, Gianmarco Alberti
>> (<gianmarcoalberti using gmail.com>) escribió:
>>> 
>>> I am building a R package, and I am facing an issue caused (as far as I understand) by the fact that some functions out of my package rely on two fuctions having the same name and coming from 2 different packages:
>>> 
>>> pROC::roc
>>> spatstat::roc
>>> 
>>> When checking the package via devtools::check(), I get the following warning:
>>> 
>>> Warning: replacing previous import ‘spatstat::roc’ by ‘pROC::roc’ when loading ‘GmAMisc’
>>> 
>>> Note that both packages are listed among the Imports in my package's DESCRIPTION file, and that (within my functions) I have actually used spatstat::roc and pROC::roc where needed.
>> I see:
>> Depends: R (>= 3.4.0), ggplot2, ggrepel, rgdal, rgeos, raster, sp,
>> spatstat, maptools, spatialEco, dismo, pROC, kimisc, corrplot,
>> InPosition, lsr, gridExtra, caTools, plyr, classInt, coin, DescTools,
>> rWind, shape, rworldmap, cluster, RcmdrMisc, gdistance, Hmisc
>> In general, it is not a good idea to depend on so many packages,
>> because what "Depends" do is to load and attach packages. Among other
>> issues, there is one that you are already experimenting: "roc" is
>> exported both by "spatstat" and "pROC", so one masks the other.
>> The solution is to list them under "Imports" instead of "Depends". In
>> fact, my advice is to put as many packages as possible under
>> "Imports". Keep in "Depends" only those you would load and attach
>> anyway when working with your package, because you need all the
>> functions along with the ones your package exports. For the rest of
>> them, just use them as package::function to avoid this kind of
>> problem, and reexport functions selectively if needed.
>> Iñaki
>> PS: I'm taking a look at other packages and I see that you always use
>> "Depends" and never "Imports". My general advice is against this
>> practice. Moreover, from the "Writing R Extensions" manual:
>> "Field ‘Depends’ should nowadays be used rarely, only for packages
>> which are intended to be put on the search path to make their
>> facilities available to the end user (and not to the package itself):
>> for example it makes sense that a user of package 'latticeExtra' would
>> want the functions of package 'lattice' made available."
>>> 
>>> I have done some web-search but I could not locate any workaround that actually fixes my issue.
>>> 
>>> Do you have any suggestion on the matter?
>>> 
>>> **************************************
>>> Dr Gianmarco Alberti (PhD)
>>> (currently)
>>> Research Support Officer II
>>> Department of Classics and Archaeology
>>> Faculty of Arts
>>> University of Malta
>>> 
>>> (starting from 3rd September 2018)
>>> Lecturer in Spatial Forensics
>>> Department of Criminology
>>> Faculty for Social Wellbeing
>>> University of Malta
>>> https://www.researchgate.net/profile/Gianmarco_Alberti4
>>> http://cainarchaeology.weebly.com/
>>> **************************************
>>> 
>>> 
>>>         [[alternative HTML version deleted]]
>>> 
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> 
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--
Rainer M. Krug, PhD (Conservation Ecology, SUN), MSc (Conservation Biology, UCT), Dipl. Phys. (Germany)

University of Zürich

Cell:       +41 (0)78 630 66 57
email:      Rainer using krugs.de
Skype:      RMkrug

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