Le 1 sept. 2014 à 11:48, Dr Gregory Jefferis <jeffe...@mrc-lmb.cam.ac.uk> a écrit :
> Hello, > > I have a more or less complete Rcpp(Eigen) dependent package that exposes a > pair of C++ classes to R using RcppModules;the C++ classes (which implement k > nearest neighbour search trees) differ only in their scalar storage type > (float vs double) and are called WKNND and WKNNF. For future > flexibility/maintenance I would have like to convert the C++ classes to > templated code. Is it possible to use RcppModules to expose template classes? > I know that Rcpp in general can be used with template classes, but the > RcppModules manual does not seem to mention this. > > I have tried to implement this by simple translation of my existing code to a > single WKNN class and then defining types for WKNND and WKNNF (i.e. double > and float). However this falls over with errors/notes indicating that the > automatic wrap/conversion of Eigen types is failing to pick up the typedef. > Error: > > In file included from WKNND.cpp:1: > In file included from > /Library/Frameworks/R.framework/Versions/3.1/Resources/library/Rcpp/include/Rcpp.h:27: > In file included from > /Library/Frameworks/R.framework/Versions/3.1/Resources/library/Rcpp/include/RcppCommon.h:169: > In file included from > /Library/Frameworks/R.framework/Versions/3.1/Resources/library/Rcpp/include/Rcpp/as.h:25: > /Library/Frameworks/R.framework/Versions/3.1/Resources/library/Rcpp/include/Rcpp/internal/Exporter.h:31:28: > error: no matching constructor for initialization of 'WKNN<double>' > Exporter( SEXP x ) : t(x){} > ^ ~ > and notes like: > > ./WKNN.h:14:8: note: candidate constructor (the implicit copy constructor) > not viable: cannot convert argument of incomplete type 'SEXP' (aka 'SEXPREC > *') to 'const WKNN<double>' > struct WKNN { > ^ > ./WKNN.h:16:3: note: candidate constructor not viable: cannot convert > argument of incomplete type 'SEXP' (aka 'SEXPREC *') to 'const > Eigen::Map<Eigen::Matrix<double, Dynamic, Dynamic> >' > WKNN(const Eigen::Map<Eigen::Matrix<T, Dynamic, Dynamic> > data, bool > buildtree=true); > ^ > > So is there a way round this? Do I have to write an explicit wrap function? > Do I have to give up on using RcppModules altogether? Any advice or pointers > to a package already doing this would be much appreciated. And of course big > thanks to Dirk, Romain and Douglas et al for these great packages. > > Best wishes, > > Greg. > > PS Code on this branch: > > https://github.com/jefferis/nabor/tree/feature/template-WKNN > > with these 2 commits making the changes: > > https://github.com/jefferis/nabor/commit/fa85ddae5187f1e93801d7ec36d1d78923384cc6 > https://github.com/jefferis/nabor/commit/9ff93e63023b2f6d9c7ddad54fb7d1f503685b86 Hi, This looks related to what RCPP_EXPOSED_CLASS does, perhaps because your class comes from a template, you could try RCPP_EXPOSED_CLASS_NODECL instead. The only difference is that it does not add the class forward declaration, so you'd have to have it after you have defined or declared your class. Romain _______________________________________________ Rcpp-devel mailing list Rcpp-devel@lists.r-forge.r-project.org https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel