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[Rcpp-devel] exposing C++ function with formal argument specification

1 message · Romain Francois

Original
Romain Francois
# 
Hello,

I commited some code that allows one to declare formal argument 
specification for an exposed C++ function. Here is an example:

require( inline )
require( Rcpp )


fx <- cxxfunction(, "", includes =
'using namespace Rcpp ;

double norm( double x, double y ){
     return sqrt( x*x + y*y ) ;
}

RCPP_MODULE(mod){
     function( "norm", &norm, List::create( _["x"] = 0.0, _["y"] = 0.0 
), "bla bla nla" ) ;
}
', plugin = "Rcpp" )

mod <- Module( "mod", getDynLib(fx) )
norm <- mod$norm

 > norm()
[1] 0

 > norm( x = 3, y = 4 )
[1] 5



It is also possible to set a formal argument with no default value:

function( "norm", &norm, List::create( _["x"] = 0.0, _["y"] = 
R_MissingArg  ), "bla bla nla" ) ;

or even to use the ...

function( "norm", &norm, List::create( _["x"] = 0.0, _["..."] = 
R_MissingArg  ), "bla bla nla" ) ;

Romain