Best way to implement optional functions?

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.

Regards,
Richie

Learning R
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