On Oct 29, 2009, at 13:56 , Seth Falcon wrote:
On 10/29/09 7:38 AM, Abhijit Bera wrote:Can't find the source to Rf_lang* series of functions. :| But I'm thinking it should be like this correct me if I'm wrong: PROTECT(e=lang4(install("myfunction"),arg1,arg2,arg3); PROTECT(SETCAR(CDR(e),portConstraints)); PROTECT(portVal=R_tryEval(e,R_GlobalEnv, NULL));Perhaps I'm misunderstanding your goal, but I do not think this is correct.After this call: > PROTECT(e=lang4(install("myfunction"),arg1,arg2,arg3); e can be visualized as: (myfunction (arg1 (arg2 (arg3 nil)))) If you want to end up with: (myfunction (arg1 (arg2 (arg3 (arg4 nil)))))Then you either will want to build up the pair list from scratch or you could use some of the helpers, e.g. (all untested),SEXP last = lastElt(e); SEXP arg4Elt = lang1(arg4); SETCDR(last, arg4Elt);
In general, I'd avoid SETCDR -- why not use CONS/LCONS? That is the generic way to do this (I'd suggest some reading about the fundamentals of it) -- langX/listX are just convenience macros (although not really macros ..).
Cheers, Simon ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
