>>>>> "CG" == Christophe Genolini <cgeno...@u-paris10.fr>
>>>>> on Tue, 09 Jun 2009 22:11:51 +0200 writes:
CG> Hi all,
CG> I am programming using S4. I define two classes, "B" is inheriting from
CG> "A". Apparently (at least since version 2.9.0 ?), when the correct
CG> signature is not find,
CG> R prefers to chose a signature in the ancestor BEFORE a signature in
the
CG> class. This is very strange to me...
CG> If I define plot for ("A",missing) and ("B",ANY), calling
CG> plot("B",missing), I would expect R to chose plot("B",ANY) before
CG> plot("A",missing)
CG> ------------------ (translate from french) --------
CG> Note : method with signature "A#missing" chose for function "plot",
CG> signature cible "B#missing".
CG> "B#ANY" could also be compatible
Yes, method dispatch had indirectly been greatly improved
in 2.9.0, as the elimination of duplicate superclasses and a
consistent (superclass) ordering was introduced.
Look at
?Methods
and skip to its references (simply "sr" in ESS),
finding
Chambers, John M.(2009) _Developments in Class Inheritance and
Method Selection_ <URL:
http://stat.stanford.edu/~jmc4/classInheritance.pdf>.
which is very recommended, and, BTW, as I just notice, has been
updated in the very last few days,
judging from my earlier reading; the updates include new
features of class definition / method dispatch in the situation
where S3 and S4 are intermingled.
Regards,
Martin Maechler, ETH Zurich
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