[R] lang2(...) with two and more arguments

[Prof Brian Ripley]

You set the first argument to x and then to y.  Why are you surprised?

On Mon, 3 Nov 2003, [koi8-r] "Timur Elzhov[koi8-r] "  wrote:

> Dear R-help,
> 
> how could I create an R call in C code using lang2 with 2 and more
> arguments? I tried this code:
> 
> SEXP f(SEXP fn, SEXP rho)
> {
>     SEXP R_fcall, x, y;
> 
>     PROTECT(R_fcall = lang2(fn, R_NilValue));
>     PROTECT(x = allocVector(REALSXP, 1));
>     PROTECT(y = allocVector(REALSXP, 1));
> 
>     REAL(x)[0] = 10;
>     REAL(y)[0] = 20;
> 
>     SETCADR(R_fcall, x);
>     SETCADR(R_fcall, y);
> 
>     UNPROTECT(3);
> 
>     return R_fcall;
> }
> 
> .Call("f", c, new.env()) returns
> 
> `.Primitive("c")(20)', but not `.Primitive("c")(10, 20)',
> as I expected. How can I recieve the disired result?
> 
> Thank you very much.
> 
> --
> WBR,
> Timur.
> 
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> 
> 

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595