[Rcpp-devel] Pass an Rcpp module object to a method belonging to another module from R?

[Grant Brown]

Thanks for the feedback, I'll definitely consider those options.

My original motivation (besides the sheer convenience of Rcpp modules as a
way to move work into C++ land) was that there's a lot of data and model
specification information that needs to migrate from R user land to the
lower level library, and I didn't want the main model object to have to
keep track of too much state (or have too huge of a constructor).

My fallback should this prove unfeasible will probably be to put  together
an R layer which can collect and validate the requisite components before
providing them to the giant constructor.

Thanks!



On Tue, Sep 9, 2014 at 8:16 PM, Dirk Eddelbuettel <edd at debian.org> wrote:

>
> On 9 September 2014 at 19:56, Grant Brown wrote:
> | Hi folks,
> |
> | I'm building several Rcpp modules which specify parts of a complicated
> | statistical model, and want to pass them to a main module for use. Is
> there an
> | easy way to do this?
> |
> | Below is a simplified example, with question marks where I'm not sure
> what to
> | do. I've tried accepting a pointer to A, playing with using XPtrs, and a
> bunch
> | of things which made far less sense, but so far no luck.
> |
> | Any suggestions or links to sections of the docs I should revisit would
> be
> | appreciated.
>
> That's neat and somewhat ambitious. Not sure it can be done; Romain may
> have
> pointers for you.
>
> I prefer to keep things simple; at least initially.  I sometimes create a
> larger class (possibly as a singleton) and then have accessors from R which
> initialize, supply parameters, alter parameters, request computation, ...
> You
> can then play with factories, and components, and inheritance, etc pp.
>
> By keeping the interface simple I can set it up in a way which lets me test
> the functionality also in a simple main away from R.  But that may just be
> me.
>
> Dirk
>
>
> | Thanks,
> | -Grant
> |
> |
> | ## file: A.cpp
> |
> | class A
> | {
> | public:
> | A();
> | ~A();
> | };
> |
> | class B
> | {
> | public:
> | B();
> | void DoSomethingWithInstanceOfA(???);
> | ~B();
> | };
> |
> | A::A()
> | {
> | // Do stuff
> | }
> |
> | B::B()
> | {
> | // Do stuff
> | }
> |
> | B::DoSomethingWithInstanceOfA(???)
> | {
> | // Do stuff
> | }
> |
> | RCPP_MODULE(mod_A)
> | {
> | using namespace Rcpp;
> | class_<A>( "A" )
> | .constructor();
> | }
> |
> | RCPP_MODULE(mod_B)
> | {
> | using namespace Rcpp;
> | class_<B>( "B" )
> | .constructor()
> | .method("DoSomethingWithInstanceOfA", &B::DoSomethingWithInstanceOfA);
> | }
> |
> |
> | ### End pseduo c++ code
> |
> |
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>
> --
> http://dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org
>
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