Hi,
I just commited Rcpp::fixed_call to support uses of STL algorithms such
as std::generate.
Here is an example that mimics :
> lapply( 1:10, function(n) rnorm(10) )
using Rcpp API :
funx <- cfunction(signature(), '
Language call( Function("rnorm"), 10 ) ;
std::vector< std::vector<double> > result(10) ;
std::generate(
result.begin(), result.end(),
fixed_call< std::vector<double> >(call)
) ;
return wrap( result );
', Rcpp = TRUE, verbose = FALSE, includes = "using namespace Rcpp;" )
Note that fixed_call embeds the return type, in that case
std::vector<double> which internally triggers an explicit as.
Here is the actual code of fixed_call:
template <typename OUT=SEXP>
class fixed_call {
public:
typedef OUT result_type ;
fixed_call( Language call_ ) : call(call_){}
fixed_call( Function fun ) : call(fun){}
OUT operator()(){
return as<OUT>( call.eval() ) ;
}
private:
Language call ;
} ;
Romain
--
Romain Francois
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http://romainfrancois.blog.free.fr
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