On 12-09-10 12:11 PM, Bert Gunter wrote:
Hi Folks:
I'm writing a little package that may not ever hit CRAN or even be
distributed beyond a relatively narrow audience at my company.
Nevertheless, I have tried to adhere to practices that would work if
it were. With that in mind, I have read the Writing R Extensions
Manual (and my humble kudos to its writers, as it has successfully
guided even an ignoramus like myself ) and Luke Tierney's R Newsletter
documentation on Namespaces. However, it is still not clear to me (see
above ignoramus comment!) what functions -- and especially which S3
methods whose generics I define in my package -- should be exported
and which should not. Perusing other packages also didn't reveal any
clear patterns from which I could infer best practice.
So may I ask for advice or any references that would provide such
guidelines. Feel free to keep replies private if this query in not
appropriate for this list. Many thanks.
If you export it, then you need to document it, and it needs to be
usable by others.
Often you'll have specialized functions in a package that do what you
need, but they are too specialized to be useful to others: don't export
those.
Once you export a function, people (or maybe just yourself in some other
package or script) will start using it, so you tend to get locked in to
the interface. So don't export functions unless you want to support
them in their current form for the life of the package.
If you export a function with the same name as one exported from another
package, it becomes inconvenient to use either function once both
packages are attached. (Which one you get depends on the order of
attaching the packages.) So don't export trivial functions, and think
carefully about the names you use for the ones you do export.
It is slightly less convenient to test or inspect functions if you don't
export them (you need the package:::foo style to refer to them from the
console). So during early development, you may want to export more, and
limit the exports when you are happy with the package.
Duncan Murdoch
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
