If one accidentally calls match(x, obj), where obj is any S4 instance, the result is NA.
I was expecting an error because, in general, if a match method is not defined for a particular S4 class, I don't know what a reasonable default could be. Specifically, here's what I see setClass("FOO", representation(a="numeric")) foo <- new("FOO", a=10) match("a", foo) [1] NA And my thinking is that this should be an error, along the lines of match("a", function(x) x) Unless, of course, a specific method for match, table="FOO" has been defined. + seth ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel