R语言中，简单的S3和S4类的定义
# S3 class
newstudent <- function(sid, sname, ssex){
tmp <- list(id = sid, name = sname, sex = ssex)
class(tmp) <- "student"
return(tmp)
}
print.student <- function(st){
cat(st$id, "\n")
cat(st$name, "\n")
cat(st$sex, "\n")
}
st = newstudent(11, "jack", "male")
#print(st)
st
# S4 class
setClass("student",
representation(
id = "numeric",
name = "character",
sex = "character"
))
# print is not a S4 generic. show methods are mapped to print for convenience, though.
setMethod("show", "student",
function(object){
cat(object@id, "\n")
cat(object@name, "\n")
cat(object@sex, "\n")
})
st = new("student", id = 41, name = "tom", sex = "male")
#print(st)
st
