[Rd] [External] Re: svd() results should have a class

[Gabriel Becker]

This does make sense to me, though I admit to not feeling super strongly
about it. Particularly in the light of the precedent from qr().

It would also be "mostly" backwards compatible, as there would not be
methods for the new class for existing code to get hung up on out of the
gate. Particularly, if class(svd(...)) was c("svd", "list") to ensure
existing methods were always hit. I don't have a great sense of the
difference in end behavior between doing that and just having the class e
"svd", though.

Should we add this as a very late addition to the Bug BBQ list for further
discussion?

~G

On Thu, Jun 23, 2022 at 5:08 PM Lenth, Russell V <russell-lenth using uiowa.edu>
wrote:

> Bob,
>
> I'm not talking about using svd as a generic method. I am talking about a
> method FOR svd results, e.g. an S3 method like foo.svd(), for which there
> already exist other methods, say foo.default and foo.qr. Currently if I
> wanted to do
>
>     svdobj <- svd(x)
>     foo(svdobj)
>
> it would not dispatch correctly because there is no svd class. Instead, it
> would be handled by foo.list if it exists, and it is certainly not clear
> that foo.list would do the right thing.
>
> Russ
>
> Sent from my iPad
>
> On Jun 23, 2022, at 6:53 PM, Robert Harlow <rharlow86 using gmail.com> wrote:
>
> 
> Don't have a view on whether it makes sense in base R or not, but WRE
> section 7.1 may be helpful to you:
> https://cran.r-project.org/doc/manuals/R-exts.html#Adding-new-generics.
>
> It's not uncommon for packages to want to make base methods generic and
> the above link provides advice on how to do so.
>
> Bob
>
> On Thu, Jun 23, 2022 at 12:07 PM Lenth, Russell V <russell-lenth using uiowa.edu
> <mailto:russell-lenth using uiowa.edu>> wrote:
> Dear R-Devel,
>
> I noticed that if we run base::svd(x), we obtain an object of class
> "list". Shouldn't there be an "svd" class, in case someone (e.g., me) wants
> to write methods for singular value decompositions? Note that other
> matrix-decomposition routines like qr() and eigen() each return objects
> having those names.
>
> Thanks
>
> Russ Lenth
> Russell-lenth using uiowa.edu<mailto:Russell-lenth using uiowa.edu>
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-devel using r-project.org<mailto:R-devel using r-project.org> mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
>         [[alternative HTML version deleted]]
>
> ______________________________________________
> R-devel using r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>

	[[alternative HTML version deleted]]