R devel - Dec 2008 - issue with [[<-Call

The following code works in Splus but not in R

coxph <- function(formula, data, weights, subset, na.action,
	init, control, method= c("efron", "breslow",
"exact"),
	singular.ok =TRUE, robust=FALSE,
	model=FALSE, x=FALSE, y=TRUE, ...) {

    method <- match.arg(method)
    Call <- match.call()

    # create a call to model.frame() that contains the formula (required)
    #  and any other of the relevant optional arguments
    # then evaluate it in the proper frame
    temp <- call('model.frame', formula=formula)
    for (i in c("data", "weights", "subset",
"na.action")) #add optional args
        if (!is.null(Call[[i]])) temp[[i]] <- Call[[i]]

    if (is.R()) m <- eval(temp, parent.frame())
    else        m <- eval(temp, sys.parent())

---------------------------------

 The problem is that the names ('data', 'weights', etc) do no
propogate over
to temp, the new call object.  It looks like an oversight in the replacement 
method.

  Priority: low.  I have other code forms that work in both dialets.
 
  I created this when teaching an internal class on S programming; the goal
was to make what was happening as transparent as possible.  If anyone has
something that they think is even better from a teaching point of view I'd
be delighted to see it.

	Terry T.

On Thu, 25 Dec 2008, Terry Therneau wrote:
>  The following code works in Splus but not in R
>
> coxph <- function(formula, data, weights, subset, na.action,
> 	init, control, method= c("efron", "breslow",
"exact"),
> 	singular.ok =TRUE, robust=FALSE,
> 	model=FALSE, x=FALSE, y=TRUE, ...) {
>
>    method <- match.arg(method)
>    Call <- match.call()
>
>    # create a call to model.frame() that contains the formula (required)
>    #  and any other of the relevant optional arguments
>    # then evaluate it in the proper frame
>    temp <- call('model.frame', formula=formula)
>    for (i in c("data", "weights", "subset",
"na.action")) #add optional args
>        if (!is.null(Call[[i]])) temp[[i]] <- Call[[i]]
>
>    if (is.R()) m <- eval(temp, parent.frame())
>    else        m <- eval(temp, sys.parent())
>
> ---------------------------------
>
> The problem is that the names ('data', 'weights', etc) do
no propogate over
> to temp, the new call object.  It looks like an oversight in the
replacement
> method.

        if (!is.null(Call[[i]])) temp[ i ] <- Call[[i]]

should do it in R at least.

HTH,

Chuck

>
>  Priority: low.  I have other code forms that work in both dialets.
>
>  I created this when teaching an internal class on S programming; the goal
> was to make what was happening as transparent as possible.  If anyone has
> something that they think is even better from a teaching point of view
I'd
> be delighted to see it.
>
> 	Terry T.
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
Charles C. Berry                            (858) 534-2098
                                             Dept of Family/Preventive Medicine
E mailto:cberry at tajo.ucsd.edu	            UC San Diego
http://famprevmed.ucsd.edu/faculty/cberry/  La Jolla, San Diego 92093-0901