[Rd] No is.formula()
Prof Brian Ripley
ripley at stats.ox.ac.uk
Thu Aug 26 09:42:22 CEST 2004
On Thu, 26 Aug 2004, Martin Maechler wrote:
> >>>>> "tony" == A J Rossini <rossini at blindglobe.net>
> >>>>> on Wed, 25 Aug 2004 14:33:23 -0700 writes:
> tony> "Warnes, Gregory R"
> tony> <gregory_r_warnes at groton.pfizer.com> writes:
> >> There appears to be no "is.formula()" function in
> >> R-1.9.1. May I suggest that
> >> is.formula <- function(x) inherits(x, "formula")
> >> be added to base, since formula is a fundimental R type?
> tony> why not just
> tony> is(x,"formula")
> tony> ?
> because the latter needs the methods package and base functions
> must work independently of "methods".
(It would be a `stats' function, I believe, but equally true.)
> The question is what "fundamental R type" would be exactly.
> But I tend to agree with Greg, since formulae are constructed
> via the .Primitive '~' operator.
> Apropos, I believe we should move the is.primitive function
> from "methods" to "base".
Given how long we have lived without either (methods needs is.primitive
for its internal workings, only) I believe we should continue to do so.
May I remind people that our aim is for base to be as lean as possible,
since we now use R *a lot* for computations during installation, checking
etc. This discourages adding trivial wrappers like these, especially to
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
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