[Rcpp-devel] template functions with Rcpp

[daniel castro]

Thank you Kevin, I'll try another approach but only knowing that I can't do
it that way is useful for me.

Regards
Daniel
El 02/05/2015 07:40, "Kevin Ushey" <kevinushey at gmail.com> escribió:

> Hi Daniel,
>
> Unfortunately, you cannot use // [[Rcpp::export]] to automagically export
> template functions.
>
> The general alternative approach is to define a template implementation,
> and then dynamically dispatch to that implementation, e.g.
>
>    template <typename T>
>    void doStuffImpl() { ... }
>
> with dispatch as
>
>    // [[Rcpp::export]]
>    void doStuff(SEXP object) {
>        switch (TYPEOF(object)) {
>        case INTSXP: return doStuffImpl<IntegerVector>();
>        case REALSXP: return doStuffImpl<NumericVector>();
>        ...
>        }
>    }
>
> Of course, the way you implement your dispatch could differ, but generally
> you need to manually map the opaque SEXP type to the appropriate Rcpp type
> (or otherwise)
>
> Hope this helps,
> Kevin
>
> On Friday, May 1, 2015, daniel castro <danielcastrob at gmail.com> wrote:
> > Hello,
> >
> > I'm trying to build a function that calculates (for example) the log
> > of all elements of a container. I want this container to be a vector,
> > a Rcpp::numericVector , or perhaps a arama::colvec , so I'm trying
> > with templates ,and it compiles without the // [[Rcpp::export]] part,
> > but when I put it to export to R it doesn't work:
> >
> > //declaration
> > template<class T>
> > T Vlog(T vectorForm);
> >
> > //code
> > // [[Rcpp::depends(RcppArmadillo)]]
> > // [[Rcpp::export]]
> > template<class T>
> > T Vlog(T vectorForm)
> > {
> >
> >
> >    std::transform(vectorForm.begin(), vectorForm.end(),
> > vectorForm.begin(), log);
> >    return vectorForm;
> > }
> >
> >
> > gives 'T' was not declared in this scope.
> >
> > if possible, How could I fix it?
> >
> > Thank you in advance
> > Daniel,
> > _______________________________________________
> > Rcpp-devel mailing list
> > Rcpp-devel at lists.r-forge.r-project.org
> > https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
> >
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