On Tue, Aug 24, 2010 at 3:50 PM, Prof Brian Ripley <rip...@stats.ox.ac.uk> wrote: > On Tue, 24 Aug 2010, Hadley Wickham wrote: > >> Hi all, >> >> If a package suggests another package in its description, you can >> check it at runtime with requires. How do you do check if a package > > Well, not really as requires() can give an error, at least until 2.12.0 is > out. So you need to wrap it in a try/tryCatch construct. > >> is available without loading it, if you only want to access one >> function in the package namespace. > > You could use try/tryCatch on pkg::fun (which is what you need to do with > require). It is difficult (and would be fragile since the details of > metadata are definitely subject to change without notice) to ascertain what > a namespace will contain/export without loading it.
Ok, thanks. Hadley -- Assistant Professor / Dobelman Family Junior Chair Department of Statistics / Rice University http://had.co.nz/ ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
