[Rd] Inherited Methods in r-devel (for package maintainers mainly)
jmc at r-project.org
Sun Feb 1 00:15:25 CET 2009
The revisions below have been re-committed (r47803), and appear to be
compatible with the current Matrix package ('0.999375-19'). Thanks to
Martin Maechler for help with Matrix.
John Chambers wrote:
> A recently committed revison of R-devel (47740) has introduced a new
> mechanism for ordering superclasses consistently, with related changes
> for selecting inherited methods.
> As part of the process, a function testInheritedMethods has been
> introduced that examines method selection for the relevant subclasses
> and reports ambiguities.
> Maintainers of packages that have methods involving multiple arguments
> are encouraged to run testInheritedMethods for the relevant generic
> functions (e.g., the binary operators). The new method selection is
> unambiguous for single-argument selection.
> It's preferable to find such ambiguities during package development
> or revision, rather than having users encounter ambiguous method
> selection later on. In that spirit, ambiguous method selection is no
> longer a warning, just a message.
> The new mechanism for class ordering and method selection is described
> in a draft paper at
> http://stat.stanford.edu/~jmc4/classInheritance.pdf (later likely to
> be part of a submission to the R Journal).
> R-devel at r-project.org mailing list
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