On 24 May 2011 at 14:53, Romain Francois wrote:
| Le 24/05/11 13:46, Dirk Eddelbuettel a ?crit :
|>
|> On 24 May 2011 at 13:22, Christoph Bergmeir wrote:
|> | Hello everybody,
|> |
|> | I just ran into the following problem: Using Rcpp::wrap with a NULL pointer crashes my R. I'm not so sure if this is a bug or if I'm using Rcpp::wrap in a way it shouldn't be used, so I wanted to discuss this here.
|> |
|> | Here is some example code:
|> |
|> | This works fine:
|> | #-----------------------------------
|> | library(inline)
|> |
|> | src<- '
|> | const char* ret = "test";
|> | return Rcpp::wrap(ret);
|> | '
|> |
|> | fun<- cxxfunction(signature(), src, plugin="Rcpp")
|> | fun()
|> | #-----------------------------------
|> |
|> | Whereas this crashes R:
|> | #-----------------------------------
|> |
|> | src<- '
|> | const char* ret = NULL;
|> | return Rcpp::wrap(ret);
|> | '
|> |
|> | fun<- cxxfunction(signature(), src, plugin="Rcpp")
|> | fun()
|> | #-----------------------------------
|>
|> I think this is mostly of the
|>
|> Q Doctor, doctor it hurts when I do this!
|> A Well then don't it
|>
|> variety. wrap() is tasked with making a valid SEXP out of what you hand it.
|> Maybe you want to test for NULL before calling it.
|>
|> Dirk
|
| And you start sounding like Steve Jobs :-)
| Perhaps we can bring the test inside Rcpp in this wrap :
|
| inline SEXP wrap(const char* const v ){
| return Rf_mkString(v) ;
| }
|
| Not sure what the result ought to be though: NULL, NA, "" ?
Yes, when glancing at the traits header for wrap, and the internal/wrap.h
which contains this I also spotted this special case for const char*, and had
the same idea. This can hold a test for NULL.
But that said I simply fear that by accomodating const char* we set ourselves
up for the next guys sending us a void* As the saying goes, you cannot
write foolproof software as you simply attract smarter fools ;-)
We could indeed return R_NilValue in this case. But what about other 'misuses'?
Dirk
|
| Romain
|
|> | I'm using Rcpp 0.9.4 and R.2.13, which I think are the latest versions.
|> |
|> | Regards,
|> | Christoph
|> |
|> | PD: Dirk, Romain, I just read through the slides you made for this workshop a month ago. Great work! Thanks a lot!
|>
|> Thanks!
|>
|> |
|> |
|> | --
|> | Christoph Bergmeir
|> | e-mail: c.bergmeir at decsai.ugr.es
|> | Grupo SCI2S, DiCITS Lab (http://sci2s.ugr.es/DiCITS)
|> | Dpto. de Ciencias de la Computacion e Inteligencia Artificial
|> | E.T.S. Ingenierias de Informatica y Telecomunicacion
|> | Universidad de Granada
|> | 18071 - GRANADA (Spain)
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|>
|
|
| --
| Romain Francois
| Professional R Enthusiast
| +33(0) 6 28 91 30 30
| http://romainfrancois.blog.free.fr
| http://romain-francois.com
| |- http://bit.ly/hdKhCy : Rcpp article in JSS
| |- http://bit.ly/elZJRJ : Montpellier Comedie Club - Avril 2011
| `- http://bit.ly/fhqbRC : Rcpp workshop in Chicago on April 28th
|
|