On Thu, 8 Jan 2004, Heywood, Giles wrote:
> I have encountered an issue which I have been unable to resolve, involving
> an S3 generic (print) being declared S4 generic in a package, and the method
I believe you should not be doing that. The S4 generic for displaying
objects is show() and not print(). This matters because auto-printing
will use show() rather than print().
> being exported. This all works fine - the problem occurs when I try to
> import the method to another package.
The other thing I noticed is that you have `import(methods)'. That is
dangerous, as loading the methods namespace without attaching the package
is known to have problems. (Take a look at how package mle does this.)
One reason it is dangerous is the following:
R_DEFAULT_PACKAGES=NULL R
> loadedNamespaces()
[1] "base"
> .isMethodsDispatchOn()
[1] FALSE
> loadNamespace("methods")
<environment: namespace:methods>
> .isMethodsDispatchOn()
[1] TRUE
> loadedNamespaces()
[1] "base" "methods"
> library(MASS)
> detach("package:MASS")
[1] TRUE
> .isMethodsDispatchOn()
[1] FALSE
so if you only load the methods namespace, any call to detach() switches
off methods dispatch! That is not the only problem which has been noted.
--
Brian D. Ripley, [EMAIL PROTECTED]
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
______________________________________________
[EMAIL PROTECTED] mailing list
https://www.stat.math.ethz.ch/mailman/listinfo/r-devel
