On 13/09/2013 10:37 AM, Prof Brian Ripley wrote:
On 13/09/2013 14:51, Duncan Murdoch wrote: > On 13/09/2013 8:31 AM, Michael Friendly wrote: >> On 9/12/2013 1:37 PM, Duncan Murdoch wrote: >> > >> > I think this one would be fine if you had library(MASS) or >> > require(MASS) or (probably best) used MASS::loglm explicitly. It may >> > be that in the past some other package put MASS on the search list, >> > and that's why it worked before. >> > >> > The distinction is between "loading" and "attaching" a package. >> > Loading it (which would be done if you had MASS::loglm, or imported >> > it) guarantees that the package is initialized and in memory, but >> > doesn't make it visible to the user without the explicit MASS:: >> > prefix. Attaching it first loads it, then modifies the user's search >> > list so the user can see it. >> > >> > Loading is less intrusive, so it's preferred over attaching. Both >> > library() and require() would attach it. >> > >> Thanks for this explanation, but I'm still confused about how to avoid >> the wrath of the CRAN-devel >> daemon, whose appetite for new morsels of developer flesh seems ever >> increasing and makes >> keeping even a stable package up-to-date a moving target. Perhaps such >> changes in R devel >> should be announced on this list for public comment before they are >> enforced in R CMD check. > Changes are generally announced in the NEWS.Rd file long before release, > but R-devel is an unreleased version, so you won't see the news until it > is there. Announcing things that nobody can try leads to fewer useful > comments than putting them into R-devel where at least people can see > what is really happening. >> >> In vcdExtra, I use MASS::loglm in ~ 6 .Rd examples, a vignette, and also >> provide R code that >> extends *.loglm methods. All of this previously worked by including >> Suggests: MASS, ... >> Changing this to Imports: MASS seems rather heavy-handed; I don't really >> want/need all of MASS >> in my namespace, and using MASS::loglm in examples seems ugly. For now, >> I'll use >> require(MASS) in each example. > > If you need a small number of things from MASS in your package code, > then importing them explicitly is definitely the way to go, e.g. > importFrom(MASS, loglm). If you only use them in examples, I wouldn't > do that, I'd recommend Suggests and use the MASS:: prefix. Whether that > is ugly is a matter of taste: it makes it clear to a user where that > function came from, and doesn't potentially hide objects from other > packages later in the search path. > > On the other hand, require(pkg) is really simple; we have no equivalent > function that only does the loading, without attaching. > So it's hard to write > > if (requireLoadable(MASS)) { > MASS::loglm( ... ) > }?requireNamespace.
Thanks. I'll switch my packages to use that. Duncan Murdoch ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
