[Rd] Re: [R] Error message during debug (PR#6804)
Peter Dalgaard
p.dalgaard at biostat.ku.dk
Tue Apr 20 20:59:22 CEST 2004
dmurdoch at pair.com writes:
> On Tue, 20 Apr 2004 13:48:43 -0400 (EDT), "Gabor Grothendieck"
> <ggrothendieck at myway.com> wrote :
>
> >
> >In R 1.9.0 on Windows XP Pro I get an error if I try to
> >debug the identity function f shown:
> >
> > > f <- function(x)x
> > > debug(f)
> > > f(1)
> > debugging in: f(1)
> > Error in f(1) : Unimplemented feature in eval
> > > R.version.string
> > [1] "R version 1.9.0, 2004-04-12"
> >
> >Without debuggging its ok.
>
> Confirmed. It's not new in 1.9.0, it appears in 1.8.1 as well. It
> seems that a function body consisting of a single token triggers it.
> I get a crash from this variation:
>
> f <- function(x) 4
>
> Maybe the system is trying to tell us that functions this simple don't
> need debugging? ;-)
>
> I'm sending this message to r-bugs to get it into the bug list (but I
> won't have time to look at it until at least the weekend, if someone
> else wants to fix it).
Actually, ?debug says:
Currently you can only debug functions
that have bodies enclosed in braces. This is a bug and will be
fixed soon.
(and has probably said so for a very long time....)
I hadn't seen the segfault from debugging a constant before, but I
recently discovered that you *can* (sort of) debug a single-expression
function by setting options(error=recover).
--
O__ ---- Peter Dalgaard Blegdamsvej 3
c/ /'_ --- Dept. of Biostatistics 2200 Cph. N
(*) \(*) -- University of Copenhagen Denmark Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk) FAX: (+45) 35327907
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