R devel - Sep 2004 - how to use update if method for formula is not in namespace?

Dear R-devel,

I've noticed that if the method for formula is not exported in NAMESPACE,
then update() would fail.  As an example:
> library(e1071)
> data(iris)
> iris.svm <- svm(Species ~ ., data=iris)
> update(iris.svm)
Error in eval(expr, envir, enclos) : couldn't find function
"svm.formula"

The same thing happens with randomForest, because randomForest.formula() was
not exported.  Is this the intended behavior of update()?  What would be the
preferred work-around?

Best,
Andy

On Tue, 14 Sep 2004, Liaw, Andy wrote:
> Dear R-devel,
> 
> I've noticed that if the method for formula is not exported in
NAMESPACE,
> then update() would fail.  As an example:
> 
> > library(e1071)
> > data(iris)
> > iris.svm <- svm(Species ~ ., data=iris)
> > update(iris.svm)
> Error in eval(expr, envir, enclos) : couldn't find function
"svm.formula"
> 
> The same thing happens with randomForest, because randomForest.formula()
was
> not exported.  Is this the intended behavior of update()?  What would be
the
> preferred work-around?
It is.   randomForest.formula should be written to report its call as to 
randomForest.  Take a look at e.g. rlm.formula.

-- 
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