我试图用通用方法定义我自己的S4类。
setClass("MultiplyObject", representation(the.factor = "numeric"))
# Create a new instance of a class with the "new" method
multobj <- new("MultiplyObject", the.factor = 3)
# Create a new generic function definition
setGeneric("ActOnNumber", function(object, n) {
standardGeneric("ActOnNumber", n)
})
# Define the ActOnNumber method for the MultiplyObject class
setMethod("ActOnNumber", signature(object = "MultiplyObject", n = "numeric"),
function(object, n) {
object@the.factor * n
})
cat(sprintf('ActOnNumber(multobj, 4) = %.2f\n', ActOnNumber(multobj, 4)))
但是,当我获取包含上述代码的文件时,我收到错误。
> source('tests4.R')
Error in ActOnNumber(multobj, 4) :
expected a generic function or a primitive for dispatch, got an object of class "numeric"
定义ActOnNumber
函数的正确方法是什么?
答案 0 :(得分:4)
standardGeneric()
函数期望函数的名称是通用的,仅此而已。所以
setGeneric("ActOnNumber", function(object, n) {
standardGeneric("ActOnNumber")
})