R/tag-export.r

In hadley/roxygen3: In-source documentation for R

#' Namespace: tags for exporting objects
#'
#' Generally, you will only need to use a bare \code{@@export} - this will
#' inspect the documented object and automatically figure out the correct
#' export (which varies based on whether it's a function, s3 method, s4
#' class, s4 generic/method).
#'
#' The convention in \pkg{roxygen3} is that exporting a generic automatically
#' exports all associated methods. This happens automatically for S4 with
#' the \code{exportMethod} directive, but needs considerable work for S3.
#' For details, see \link{roxgyen_s3}.
#'
#' It's not recommend practice to use \code{@@exportPattern} (instead it's
#' better to individually label the functions to be exported), but this may
#' be useful for legacy packages.
#'
#' \code{@@S3method} exists largely for compatibility with roxygen2. Roxygen3
#' now automatically determines if an object is an S3 method, and so only
#' \code{@@export is necessary.}
#'
#' @tagUsage
#'   @@export
#'   @@export function name
#' @rdname tag-export
setClass("ExportTag", contains = "Tag")

setMethod("value<-", "ExportTag", function(tag, value) {
  if (isEmpty(value)) return(tag)
  tag@text <- str_split(value, "[[:space:]]+")[[1]]
  tag
})

setMethod("process", "ExportTag", function(input, block) {
  if (!isEmpty(input)) return(block)

  defaults <- tag(block, "defaultExport")
  if (isEmpty(defaults)) return(block)

  tag(block, "export") <- defaults@export
  tag(block, "exportMethods") <- suffix(defaults@exportMethods)
  tag(block, "exportClass") <- suffix(defaults@exportClass)
  tag(block, "S3method") <- new("S3methodTag", methods = defaults@S3method)
  block
})

setMethod("writeNamespace", "ExportTag", function(object) {
  ns_each("export", object@text)
})

setMethod("getPrereqs", "ExportTag", function(tag) {
  c("S3methodTag", "DocTypeTag")
})