[R] accesing slots of S4 class in C code

[Duncan Temple Lang]

You need to use .Call() rather than .C() to pass the R object
to the TestFun routine.

 D.

Aniko Szabo wrote:
> I am trying to use a custom S4 object in my C code and I cannot get the
> access to its slots working.
> 
>  
> 
> The following is a toy example, but even this crashes. 
> 
>  
> 
> In R I have:
> 
>  
> 
> setClass("pd", representation(data="numeric"))
> 
> x <- new("pd", data=1:5)
> 
>  
> 
> test <- function(pd.obj) {
> 
>   res <- .C("TestFun", pd.obj)
> 
>   res}
> 
>  
> 
> test(x)
> 
>  
> 
> (Of couse I load the DLL as well.)
> 
>  
> 
> The corresponding C file has:
> 
>  
> 
> SEXP TestFun(SEXP pd_obj)
> 
> {
> 
>  SEXP t=R_NilValue;
> 
>  PROTECT(t = GET_SLOT(pd_obj, install("data")));
> 
>  UNPROTECT(1);
> 
>  return(t);
> 
> }
> 
>  
> 
>  
> 
> What I hope to get as a result is the (1:5) vector. 
> 
> In the long term, the vector will be a multi-dimensional array and I
> will want to do calculations using its contents in the C program.
> 
>  
> 
> Thanks for any help,
> 
>  
> 
> Aniko
> 
> 
> Huntsman Cancer Institute wishes to promote open communication while protecting confidential and/or privileged information.  If you have received this message in error, please inform the sender and delete all copies.
> 
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html

-- 
Duncan Temple Lang                duncan at wald.ucdavis.edu
Department of Statistics          work:  (530) 752-4782
371 Kerr Hall                     fax:   (530) 752-7099
One Shields Ave.
University of California at Davis
Davis, CA 95616, USA



-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: not available
Url : https://stat.ethz.ch/pipermail/r-help/attachments/20050817/320752cd/attachment.bin