Help with lang4

Hi

I seem to have run into a situation where I have more than 3 arguments to
pass to a function from C.

the following functions help me build an expression for evaluation:

lang
lang2
lang3
lang4

What should one do if there are more arguments than lang4 can handle?

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));

Regards
Abhijit Bera


On Thu, Oct 29, 2009 at 7:14 PM, Seth Falcon <seth at userprimary.net> wrote:

On 10/29/09 7:00 AM, Abhijit Bera wrote:

Hi

I seem to have run into a situation where I have more than 3 arguments to
pass to a function from C.

the following functions help me build an expression for evaluation:

lang
lang2
lang3
lang4

What should one do if there are more arguments than lang4 can handle?

If you take a look at the source code for those functions, something may
suggest itself.  R function calls at the C level are composed like in lisp:
a pair-list starting with the function cons'ed with the args.

+ seth

	[[alternative HTML version deleted]]

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));

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);