Hi
In V&R the "polynomial" class is explicitly specified to have no logical operators: setMethod("Logic", signature(e1="polynomial"), function(e1,e2){stop ("...")}) I too have a class of objects for which I want to specify that Logic operators do not work, but executing setClass("brob", representation = representation (x="numeric",positive="logical"), prototype = list(x=numeric(),positive=logical()) ) setMethod("Logic",signature(e1="brob"), function(e1,e2) { stop("No logic currently implemented for brob objects") } ) gives me Error in setMethod("Logic", signature(e1 = "brob"), function(e1, e2) { : no existing definition for function 'Logic' ?Math seems to imply that there is no "Logic" group. So, what is the correct way to specify that logical operations are not allowed for "brob" objects? -- Robin Hankin Uncertainty Analyst National Oceanography Centre, Southampton European Way, Southampton SO14 3ZH, UK tel 023-8059-7743 ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel