Re: [Rd] page() (Was: Re: predict.smooth.spline.fit and Recall() (Was: Re: Return function from function and Recall()))

From: Henrik Bengtsson <hb_at_maths.lth.se>
Date: Wed 05 Apr 2006 - 14:24:53 GMT

On 4/5/06, Prof Brian Ripley <ripley@stats.ox.ac.uk> wrote:
> On Wed, 5 Apr 2006, Henrik Bengtsson wrote:
>
> > Here I think S3 dispatch is very natural. Try the following:
>
> I don't: it is documented to work on a name not an object.

What comes first, the documentation of a method or the method itself? ;)

I noticed the last year or so, that the documentation is being referred to as a requirement/design specification, in addition to being help pages. If this is in general true, that is a good guideline. Has this evolved recently, or is it just me that missed it before?

/Henrik

>
> > page <- function(x, method = c("dput", "print"), ...) UseMethod("page")
> >
> > page.getAnywhere <- function(x, ..., idx=NULL) {
> > name <- x$name;
> > objects <- x$obj;
> >
> > if (length(objects) == 0)
> > stop("no object named '", name, "' was found");
> >
> > if (is.null(idx)) {
> > # Include all non-duplicated objects found
> > idx <- (1:length(objects))[!x$dups];
> > }
> >
> > for (ii in idx) {
> > title <- paste(name, " (", x$where[ii], ")", sep="");
> > eval(substitute({
> > object <- x$obj[[ii]];
> > page(object, ...);
> > }, list(object=as.name(title))));
> > }
> > }
> >
> > page.default <- utils::page;
> >
> > page(getAnywhere("predict.smooth.spline.fit"))
> >
> > You can have page.function(), page.character(), page.environment(),
> > etc. and make these call page.default() indirectly. What I think
> > would be a very useful add on is to add an argument 'title' for which
> > you can set/override the title. Then the "ugly" substitute() calls
> > could be limited to one specific case; where a "default" object is
> > passed and no title is set.
> >
> > If you want to, I could play around with a bit.
> >
> > /Henrik
> >
> > On 4/5/06, Kurt Hornik <Kurt.Hornik@wu-wien.ac.at> wrote:
> >>>>>>> Prof Brian Ripley writes:
> >>
> >>> On Wed, 5 Apr 2006, Henrik Bengtsson wrote:
> >>>> Hi,
> >
> > [snip]
> >
> >>> As for
> >>
> >>>>> PS, may I suggest to modify page() so that
> >>>>> 'page(getAnywhere("predict.smooth.spline.fit"))' works? DS.
> >>
> >>> it is rather tricky. page() takes a name aka symbol as its argument
> >>> (and is thereby S-compatible), and also works with a bare character
> >>> string (undocumented). What you have here is a call that does not
> >>> even return a function. It is more reasonable that
> >>> stats:::predict.smooth.spline.fit should work, and it is also a call.
> >>> I have in the past thought about special-casing that, but it is a
> >>> valid name (you would have to back-quote it, but it does work). So
> >>> one possible way out would be to use get() on a name and evaluate
> >>> calls, e.g.
> >>
> >>> page <- function(x, method = c("dput", "print"), ...)
> >>> {
> >>> subx <- substitute(x)
> >>> have_object <- FALSE
> >>> if(is.call(subx)) {
> >>> object <- x
> >>> have_object <- TRUE
> >>> subx <- deparse(subx)
> >>> } else {
> >>> if(is.character(x)) subx <- x
> >>> else if(is.name(subx)) subx <- deparse(subx)
> >>> if (!is.character(subx) || length(subx) != 1)
> >>> stop("'page' requires a name, call or character string")
> >>> parent <- parent.frame()
> >>> if(exists(subx, envir = parent, inherits=TRUE)) {
> >>> object <- get(subx, envir = parent, inherits=TRUE)
> >>> have_object <- TRUE
> >>> }
> >>> }
> >>> if(have_object) {
> >>> method <- match.arg(method)
> >>> file <- tempfile("Rpage.")
> >>> if(method == "dput")
> >>> dput(object, file)
> >>> else {
> >>> sink(file)
> >>> print(object)
> >>> sink()
> >>> }
> >>> file.show(file, title = subx, delete.file = TRUE, ...)
> >>> } else
> >>> stop(gettextf("no object named '%s' to show", subx), domain = NA)
> >>> }
> >>
> >>> which also allows 1-element character vectors (and I am not entirely
> >>> sure we want that).
> >>
> >> There was a similar issue with prompt() (actually, its default method)
> >> for which I ended up "temporarily" providing the following (argh):
> >>
> >> else {
> >> name <- substitute(object)
> >> if (is.name(name))
> >> as.character(name)
> >> else if (is.call(name) && (as.character(name[[1]]) %in%
> >> c("::", ":::", "getAnywhere"))) {
> >> name <- as.character(name)
> >> name[length(name)]
> >> }
> >> else stop("cannot determine a usable name")
> >> }
> >>
> >> Best
> >> -k
> >>
> >> ______________________________________________
> >> R-devel@r-project.org mailing list
> >> https://stat.ethz.ch/mailman/listinfo/r-devel
> >
> > ______________________________________________
> > R-devel@r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-devel
> >
> >
>
> --
> Brian D. Ripley, ripley@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
>
>

--
Henrik Bengtsson
Mobile: +46 708 909208 (+2h UTC)

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Received on Thu Apr 06 00:51:04 2006

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