Roxygen2-如何@export引用类生成器? [英] Roxygen2 - how to @export reference class generator?

问题描述

例如，假设我有一个名为Test的以下程序包，并且我想导出类A:

For instance, say I have the following package called Test and I want to export class A:

# In /R/Test.R:
#' @docType package
#' @import methods
#' @exportClass A
A <- setRefClass("A", methods = list(foo = identity))

但是，在构建和加载后，使用A的生成器时出现以下错误:

However, after building and loading, I get the following error when using A's generator:

> library(Test)
> A()$foo(1)
Error: could not find function "A"

我检查了NAMESPACE文件的内容是否正常:

I've checked the contents of my NAMESPACE file is fine:

exportClasses(A)
import(methods)

那怎么了?为什么我的类生成器没有导出?

So what's going wrong? Why isn't my class generator being exported?

推荐答案

如果添加@export A，则生成器功能A也将被导出，例如

If you add @export A then the generator function A will be exported, too, e.g.

#' A class description
#'
#' @import methods
#' @export A
#' @exportClass A
A = setRefClass('A',
  fields=list(name='character', n='numeric'),
  methods=list(
    hello=function() {
      "A greeting"
      return(paste0('Hello, ', name))
    }
  )
)

重要提示:不要忘记在export指令中明确提及A，否则它似乎不起作用，与功能不同.

Important: Don't forget to explicitly mention A in the export directive or it doesn't appear to work, unlike for functions.

或者，在导出类 时，您仍然可以通过new()使用该类，例如

Alternatively, as the class is being exported, you can still use the class via new(), e.g.

> a = new('A', name='Josh', n=12345)
> a$hello()
 [1] "Hello, Josh"

但是添加导出很容易.

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