用两个参数编写S4泛型方法

时间:2014-02-23 02:11:44

标签: r s4

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?

1 个答案:

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")
})