#31 include namespace exporting and simplified function names

R/colons.R

@@ -1,51 +1,70 @@
 #' Colons
 #'
-#' Get an object from a package
+#' Get an object from a namespace
 #'
-#' @details
-#' This is a work around to calling `:::`.
+#' @details The functions mimic the use of `::` and `:::` for extracting values
+#' from namespaces.  `%colons%` is an alias for `%::%`.
 #'
-#' @section WARNING:
-#' To reiterate from other documentation: it is not advised to use `:::` in
-#'   your code as it will retrieve non-exported objects that may be more
-#'   likely to change in their functionality that exported objects.
+#' @section WARNING: To reiterate from other documentation: it is not advised to
+#'   use `:::` in your code as it will retrieve non-exported objects that may be
+#'   more likely to change in their functionality that exported objects.
 #'
 #' @param package Name of the package
 #' @param name Name to retrieve
 #' @return The variable `name` from package `package`
 #' @examples
-#' identical("base" %colons% "mean", base::mean)
-#' "fuj" %colons% "colons_example" # unexported value
+#' identical("base" %::% "mean", base::mean)
+#' "fuj" %:::% "colons_example" # unexported value
 #'
+#' @name colons
+#' @seealso `help("::")`
+NULL
+
+#' @rdname colons
 #' @export
-`%colons%` <- function(package, name) {
-  stopifnot(
-    length(package) == 1,
-    is.character(package),
-    length(name) == 1,
-    is.character(name)
+`%::%` <- function(package, name) {
+  colons_check(package, name)
+  tryCatch(
+    getExportedValue(asNamespace(package), name),
+    error = function(e) stop(cond_colons(package, name, 2))
   )
+}
 
-  require_namespace(package)
-
-  res <- try(get(name, envir = asNamespace(package)), silent = TRUE)
-
-  if (inherits(res, "try-error")) {
-    stop(cond_colons(package, name))
-  }
-
-  res
+#' @rdname colons
+#' @export
+`%:::%` <- function(package, name) {
+  colons_check(package, name)
+  tryCatch(
+    get(name, envir = asNamespace(package)),
+    error = function(e) stop(cond_colons(package, name, 3))
+  )
 }
 
-cond_colons <- function(package, name) {
+#' @rdname colons
+#' @export
+`%colons%` <- `%:::%`
+
+cond_colons <- function(package, name, n) {
   new_condition(
     msg = sprintf(
-      "`%s:::%s` not found",
+      "`%s%s%s` not found",
       as.character(package),
+      strrep(":", n),
       as.character(name)
     ),
     class = "colons"
   )
 }
 
+colons_check <- function(package, name) {
+  stopifnot(
+    length(package) == 1,
+    is.character(package),
+    length(name) == 1,
+    is.character(name)
+  )
+
+  require_namespace(package)
+}
+
 colons_example <- "Hello, world"