On Sun, May 13, 2012 at 10:14 AM, Uwe Ligges <lig...@statistik.tu-dortmund.de> wrote: > > > On 13.05.2012 10:59, Duncan Murdoch wrote: >> >> On 12-05-13 3:15 AM, Jeroen Ooms wrote: >>> >>> I have always assumed that having a package in the 'Depends' field >>> would automatically also import the namespace. However, it seems that >>> in R 2.15, dependencies do not become available until the package is >>> actually attached to the searchpath. Is this intended behavior? >>> >>> The problem appears as follows: Suppose there is a package 'Child' >>> which Depends, but does not explicitly import a package called >>> 'Parent' and contains a function that calls out to an object in the >>> namespace of 'Parent'. When this function is called without attaching >>> 'Child' to the search path, the function in 'Parent' cannot be found. >>> >>> Here an example from the manual of the bigdata package, but the >>> problem is very widespread: >>> >>> x = matrix(rnorm(50*80),50,80) >>> beta = c(3,2,1.5,rep(0,77)) >>> y = rnorm(50) + x%*%beta >>> z1 = bigdata::lasso.stars(x,y) >>> >>> The example fails because lasso.stars depends on 'glmnet' which is not >>> loaded until bigdata is attached. The only way to be able to call >>> lasso.stars is to actually attach the bigdata package: >>> >>> library(bigdata) >>> z1 = bigdata::lasso.stars(x,y) >>> >>> Now to further complicate things, it seems that this problem is >>> inherited to any 'grandchild' package that imports, in this case, the >>> lasso.stars function. I have a hard time finding a good example but I >>> am sure they are out there. >>> >>> Is this a bug? I know that it can be avoided by asking package authors >>> to use Imports instead of Depends, but in practice the majority of the >>> packages on CRAN still use Depends. It seems like the problem is >>> easily fixed if R would automatically import the namespace of any >>> Depends packages into to the child package namespace? >> >> >> Not sure if it's a bug, but the correct solution in bigdata is to import >> the glmnet function in its NAMESPACE. Then the namespace that gets >> loaded when you type bigdata::lasso.stars will be able to see the glmnet >> function. >> >> Perhaps Depends in the DESCRIPTION file should do the import >> automatically, but it will be faster to import just one function than >> everything from a package that has a lot of exports. So maybe it's a bug >> because we don't do that, but I think there would be complaints if we did. >> >> On the other hand, if bigdata::lasso.stars loaded glmnet onto the search >> path, I think that would be a bug. The search path belongs to the user, >> not to R, and the user might have used the :: notation to avoid messing >> with it. > > > I do not see any problem in R. If someone is going to import a Namespace, he > or she has to do that via import directives in the NAMESPACE file. If > someone is going to have a package on the search path, he or she has to > require() it. The DESCRIPTION file is used to derive the dependency > structures among packages for installation order, check order etc.
So should package authors both list a package in the depends of DESCRIPTION and explicitly import what is needed so if someone else uses their code without loading the package, everything needed is available? > > Best, > Uwe > > > > > >> Duncan Murdoch >> >> ______________________________________________ >> R-devel@r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-devel > > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel -- Joshua Wiley Ph.D. Student, Health Psychology Programmer Analyst II, Statistical Consulting Group University of California, Los Angeles https://joshuawiley.com/ ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
