[Rd] Best way to implement optional functions?

[Duncan Murdoch]

On 16/11/2015 4:00 AM, Richard Cotton wrote:
> On 22 October 2015 at 22:55, Duncan Murdoch <murdoch.duncan at gmail.com> wrote:
>> I'm planning on adding some new WebGL functionality to the rgl package, but
>> it will pull in a very large number of dependencies. Since many people won't
>> need it, I'd like to make the new parts optional.
>
>> Can people suggest other packages that solve this kind of problem in a good
>> way?
>
> I had the same issue with the assertive package: it was getting big,
> and not everyone wanted all the functionality.
>
> The solution was to create several smaller packages with individual
> components of functionality, for example assertive.base contains the
> bare-minimum functionality; assertive.numbers contains functionality
> related to numbers, etc.
>
> Then the assertive package imports all the functions from the
> component packages and reexports them.
>
> That way people who want a small footprint (mostly other package
> developers) can specify only what they need, and people who don't care
> (mostly end users) can just type library(assertive) and get access to
> everything.
>

When you import and re-export functions, do they need to be documented 
in both places?  I forget if we have a simple way to say "this function 
is documented in that package", to avoid duplication.

Duncan Murdoch