Le 14/08/13 16:25, Dirk Eddelbuettel a écrit :


On 14 August 2013 at 15:57, Matteo Fasiolo wrote:
|  thank you very much for your replies. In the end a named vector is
| enough for my purpose:
|
| cppFunction(
|   '
|   NumericVector myVett(NumericVector x = NumericVector::create(0) )
|  {
|   if(x.size() == 0) x = NumericVector::create(_["a"] = 1.0, _["b"] = 2.0);
|   return x;
|  }
|  '
| )

You don't even need the assignment in the function definition:

R> cppFunction("NumericVector matteo(NumericVector x) { if (x.size()==0) x = 
NumericVector(4); return(x); }")
R> matteo(vector())
[1] 0 0 0 0
R> matteo(1:3)
[1] 1 2 3
R>

Dirk

This might not stay valid code when we put more control for dispatch, argument recognition etc.

Some of that is in place with Rcpp::is, the rest will follow. We might lose things like this, but we will gain more useful things instead. And we never said passing 0 arguments to a function needing one works, so it is not a documented feature.

Romain


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