Is it possible to define a method for multiple classes (that are not simply extensions of the other) without making separate setMethod() calls? As far as I understand it, this is how to currently set methods for multiple classes: setClass("myClass1", representation=representation(x="numeric",y="numeric")) setClass("myClass2", representation=representation(x="numeric",z="character")) setGeneric("x", function(object) standardGeneric("x")) setMethod("x", signature("myClass1"), function(object) object at x) setMethod("x", signature("myClass2"), function(object) object at x) I was wondering if it is possible to do the equivalent of: setMethod("x", signature(c("myClass1","myClass2")), function(object) object at x) Or am I always required to do two separate setMethods? Thanks, -Robert Robert M. Flight, Ph.D. University of Louisville Bioinformatics Laboratory University of Louisville Louisville, KY PH 502-852-1809 (HSC) PH 502-852-0467 (Belknap) EM robert.flight at louisville.edu EM rflight79 at gmail.com Williams and Holland's Law: ? ? ?? If enough data is collected, anything may be proven by statistical methods.