gistfile1.txt

setClass("Node",
         slots = list(data="character",
                      edges="list"))

setClass("Edge",
         slots = list(weight="numeric",
                      left = "character",
                      right = "character"))

setClass("Graph",
         slots = list(nodes = "list",
             edges = "list"))

#setGeneric("==",
#           function(e1,e2) standardGeneric("=="),
#           useAsDefault = .Primitive("=="))
setMethod("==",
          c(e1="Node",e2="Node"),
          function(e1,e2) {
              e1@data == e2@data
          })