R/tag-usage.r

In hadley/roxygen3: In-source documentation for R

#' @@usage: describe the usage of a function.
#'
#' Roxygen3 will automatically generate the usage string for you - if you need
#' specify this yourself (unless you particularly want to control the formatting
#' it's probably an indiciation of roxygen bug and should be reported).
#'
#' @tagUsage @@usage f(a, b, c) # You can also comments
setClass("UsageTag", contains = "Tag",
  list(usage = "Usage"),
  prototype = list(usage = new("NullUsage")))

setMethod("value", "UsageTag", function(tag) tag@usage)
setMethod("value<-", "UsageTag", function(tag, value) {
  if (is.character(value)) {
    value <- new("TextUsage", text = value)
  }
  tag@usage <- value
  tag
})

setMethod("writeRd", "UsageTag", function(object) {
  RdCommand("usage", format(object@usage))
})

setMethod("defaultTag", c("UsageTag", "FunctionObject"),
  function(tag, object) {
    usage <- new("FunctionUsage",
      name = object@name,
      formals = as.list(formals(object@value)))
    new("UsageTag", usage = usage)
  }
)
setMethod("defaultTag", c("UsageTag", "S3MethodObject"),
  function(tag, object) {
    method <- s3_method_info(object@value)

    usage <- new("S3MethodUsage",
      generic = method[1],
      signature = method[2],
      formals = as.list(formals(object@value)))
    new("UsageTag", usage = usage)
  }
)
setMethod("defaultTag", c("UsageTag", "S4MethodObject"),
  function(tag, object) {
    obj <- object@value
    usage <- new("S4MethodUsage",
      generic = obj@generic,
      signature = obj@defined,
      formals = as.list(formals(obj@.Data)))
    new("UsageTag", usage = usage)
  }
)

setMethod("defaultTag", c("UsageTag", "S4GenericObject"),
  function(tag, object) {
    usage <- new("FunctionUsage",
      name = object@name,
      formals = as.list(formals(object@value@.Data)))
    new("UsageTag", usage = usage)
  }
)

setMethod("defaultTag", c("UsageTag", "DataObject"),
  function(tag, object) {
    usage <- new("TextUsage", text = object@name)
    new("UsageTag", usage = usage)
  }
)