Correct NAMESPACE approach when writing an S3 method for a generic in another package
I think rgl should be in Depends. You are providing a method for a generic function from another package. In order to use your method, you want the user to be able to call the generic function without scoping (i.e. without calling rgl::plot3d), so the generic should be on the search path, so the package that provides it should be listed in Depends in the NAMESPACE file. Martyn
On Fri, 2013-08-23 at 22:01 -0600, Gavin Simpson wrote:
Dear List, In one of my packages I have an S3 method for the plot3d generic function from package rgl. I am trying to streamline my Depends entries but don't know how to have plot3d(foo) in the examples section for the plot3d method in my package, without rgl being in Depends. Note that I importFrom(rgl, plotd3d) and register my S3 method via S3Method() in the NAMESPACE. If rgl is not in Depends but in Imports, I see this when checking the package
## 3D plot of data with curve superimposed plot3d(aber.pc, abernethy2)
Error: could not find function "plot3d" I presume this is because rgl's namespace is only loaded but the package is not attached to the search path. Writing R extensions indicates that one can export from a namespace something that was imported from another package namespace. I thought that might help the situation, and now the code doesn't raise an error, I get * checking for missing documentation entries ... WARNING Undocumented code objects: ?plot3d? All user-level objects in a package should have documentation entries. See the chapter ?Writing R documentation files? in the ?Writing R Extensions? manual. as I don't document plot3d() itself. What is the recommended combination of Depends and Imports plus NAMESPACE directives etc that one should use in this situation? Or am I missing something else? I have a similar issue with my package including an S3 method for a generic in the lattice package, so if possible I could get rid of both of these from Depends if I can solve the above issue. Thanks in advance. Gavin