[R-pkg-devel] Conditionally register method with generic in other package

[Joshua Ulrich]

For posterity, the solution I employed did not register the method as
a formal S3 method.  Functionality in package B was unchanged as long
as package B was loaded and attached... which was good enough for my
purposes.

On Wed, Dec 6, 2017 at 6:45 AM, Joshua Ulrich <josh.m.ulrich at gmail.com> wrote:
> I have a feeling I know the answer to this question, but I'm asking
> with the hope that I learn something new.
>
> Package A defines a S3 generic function, "foo()".  Package B defines a
> S3 class "bar", and a foo.bar() method.  This method is not strictly
> necessary for the package to function, and package A has many
> dependencies.
>
> To avoid excessive dependencies, I would like to only register
> foo.bar() if package A is installed at the time package B is
> installed.  If package A is installed after package B, then warn the
> user when package B is loaded and/or attached, so they can re-install
> A and have foo.bar() registered correctly.
>
> I could figure out a way to do this manually, but doubt it would be
> CRAN-approved.  What is the recommended way to handle this situation?
> I've received one suggestion to split B into 2 packages: one without
> the method, and one with.  Are there other alternatives?
>
> Thanks,
> Josh
>
> --
> Joshua Ulrich  |  about.me/joshuaulrich
> FOSS Trading  |  www.fosstrading.com
> R/Finance 2018 | www.rinfinance.com



-- 
Joshua Ulrich  |  about.me/joshuaulrich
FOSS Trading  |  www.fosstrading.com
R/Finance 2018 | www.rinfinance.com