如何为继承的插槽定义S4原型 [英] How to define an S4 prototype for inherited slots

问题描述

我有一个基类(我们称其为"A")，其表示对于许多其他类是通用的.

I have a base class (let's call it "A") whose representation is common to many other classes.

因此，我定义了其他类(例如"B")来包含该类.

Therefore I define other classes, such as "B", to contain this class.

我想将这些其他类(B)的原型设置为包括从A继承的插槽的默认值.我认为这很自然:

I would like to set the prototype of these other classes (B) to include the default values for the slots inherited from A. I thought this would be natural:

setClass("A", representation(a="character"))
setClass("B", contains="A", prototype(a = "hello"))

但是会产生错误:

Error in representation[!slots] : object of type 'S4' is not subsettable

不确定为什么会这样.如果我省略了原型，我可以做:

Not sure why this happens. If I omit the prototype I can do:

setClass("B", contains="A")

然后破解我自己的生成器函数:

and then hack my own generator function:

new_B <- function(...){ 
           obj <- new("B", ...)
           obj@a = "hello"
           obj
         }

，然后使用new_B()基于原型创建我的对象，但是与使用通用生成器new("B")并拥有我的原型相比，这是非常粗陋和丑陋的.

and then create my object based on the prototype with new_B(), but that's terribly crude and ugly compared to using the generic generator new("B") and having my prototype...

推荐答案

您只需要命名参数即可:

You just need to name the argument:

setClass("A", representation(a="character"))
setClass("B", contains="A", prototype=prototype(a="hello"))

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