[R] recover should send messages to stderr, not stdout

[Prof Brian Ripley]

On Wed, 12 May 2004, Vadim Ogranovich wrote:

> 
> 
> > -----Original Message-----
> > From: Prof Brian Ripley [mailto:ripley at stats.ox.ac.uk] 
> > Sent: Tuesday, May 11, 2004 11:21 PM
> > To: Vadim Ogranovich
> > Cc: R-Help
> > Subject: Re: [R] recover should send messages to stderr, not stdout
> > 
> ...
> > 
> > Note that some of us consider recover() to be designed for 
> > interactive-only use, and use something like
> 
> Unfortunately, R help doesn't reflect the apparent diversity of
> opinions. Regarding recover it says

Well, I got my suggestion from the work of the author of those words,
on page 268 of the Green Book, so I don't think your `apparent' is based 
on careful reading.

>      The use of 'recover' largely supersedes 'dump.frames' as an error
>      option, unless you really want to wait to look at the error.  If
>      'recover' is called in non-interactive mode, it behaves like
>      'dump.frames'.  <...>
> 
> >     options(error=expression(if(interactive()) recover() else 
> > dump.calls()))
> 
> This is useful. Thank you very much for the tip!
> 
> > On Tue, 11 May 2004, Vadim Ogranovich wrote:
> > 
> > > recover() sends all its messages, which I consider to be error 
> > > messages, to stdout. I think they more properly belong to stderr.
> > >  
> > > This is an important difference for those of us who use R in batch 
> > > mode to generate ASCII files.
> > 
> > Only to the subset who believe that recover() is a useful 
> > error option in 
> > non-interactive use.
> 
> This subset is likely to include everyone who carefully reads the
> documentation, see the above excerpt from a help page.

Everyone who reads that carefully will realize that in batch use you do
want (and need) to wait for the error.

-- 
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