These look like important improvements.  As a relative newcomer to the R
community, I'm not sure I understand what the procedures are for such
changes.

In particular, does the fact that the changes were committed to R-devel mean
that the changes have already been reviewed and approved by R Core?  Are R
Core's discussions / deliberations archived somewhere? What is the role of
the larger R community in reviewing and approving changes like this?

How is documentation handled? Who is responsible for developing and
maintaining a definitive reference manual (not just man pages) which
includes all the cumulative changes and describes them comprehensively and
in black-box way (not referring to history and implementation details)?

Thanks,

           -s

On Sun, Apr 26, 2009 at 3:58 PM, John Chambers <jmc@r-project.org> wrote:

> Changes were committed today to the r-devel version of R to make S4 and S3
> classes (and abnormal object types such as "environment") work together more
> consistently.
>
> Basically, S4 classes can now contain any S3 class or object type, and
> should now inherit S3 methods for these.  Also, the main practical problem
> with defining S3 methods for other S4 classes (namely, that S4 inheritance
> was not recognized) has been fixed, to the extent possible.
>
> See ?Methods (especially the section on S3 methods).  For details (there
> are quite a few) see the paper referenced there,
>  http://stat.stanford.edu/~jmc4/classInheritance.pdf<http://stat.stanford.edu/%7Ejmc4/classInheritance.pdf>
>
> Since these changes arguably fix design flaws, I would like to see them in
> 2.9.1, so please test them out.  For the moment, they are only in the
> r-devel version.
>
> There can be changes to current behavior.  For example, I found one
> regression test for S4 methods that only worked because an apparent S3
> method, sort.list, was NOT inherited by an S4 class that contained "list".
>
> John
>
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