[Rcpp-devel] Question regarding integrating preexisting C++ code via Rcpp

[Romain François]

Hello,

It looks like you want to use Rcpp modules. See the "Rcpp-modules" vignette.

 > require( Rcpp )
 > vignette( "Rcpp-modules" )

Or from CRAN:

http://cran.r-project.org/web/packages/Rcpp/vignettes/Rcpp-modules.pdf

Modules are still in (slow) dev, so they lack some features, but what 
exists already might answer your needs.

Romain

Le 10/10/11 12:09, Simon Fuller a écrit :
> Hello,
>
> I have just joined the mailing list.
>
> I was hoping you might be able to help me with a question.
>
> I am new to Rcpp, have some experience with both R and C++, but very 
> little experience with integrating languages.
>
> I hope to use Rcpp to develop code over the next few years. However, 
> to begin with, I have some preexisting C++ classes that I would like 
> to make available to R.
>
> I have read the documentation that I can find, but I do not know which 
> is the best approach to take.
>
> I only, in principle, need /one method/ to interact with the classes - 
> there then follows a fairly arduous process using different tree 
> structures each of which have aggregate classes, but only a single 
> double needs to be returned to R.
>
> I was therefore hoping to simply call a C++ wrapper function in-line, 
> remotely, which in turn called my classes, but that does not work. I 
> get an:
> "expected unqualified-id before 'extern' " error after my includes, 
> at: RcppExport SEXP..  at the start of my method declaration. (I can 
> post code if this approach is not a complete dead end)
>
> So my two questions are: is there a quick way of prototyping this? 
> i.e. to get R to invoke my classes through an rcpp intermediary.
>
> If there is not a quick way to do this, what is the best approach? Do 
> I need to, and if so how do I, make my classes accessible to Rcpp. 
> Because my whole hope here is to use preexisting code as swiftly as 
> possible, 'easiest' and 'quickest' are almost synonyms for 'best' in 
> my question.
>
> If someone could point me in the direction of some example code where 
> Rcpp invokes user classes this would be great.
>
> My apologies if my question has been covered before, but I would 
> really appreciate some advice on what is and is not possible, and some 
> strategic advice on the best (easiest and quickest) approach.
>
> Thank you for your help. It is deeply appreciated.
>
> Simon
>
>
>
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-- 
Romain Francois
Professional R Enthusiast
http://romainfrancois.blog.free.fr

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