Async initialization for DateFormat

pkg/intl/lib/date_format_internal.dart

+// Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+/**
+ * This contains internal implementation details of the date formatting code
+ * which are split out into a separate library because they require public

[Emily Fortuna, 2012/09/04 20:14:42]

"split out into separate libraries"?

[Alan Knight, 2012/09/04 23:39:03]

I don't think so. The methods (plural) are split out into this library
(singular). But obviously it's not very clear. Rephrased.

+ * functions (called across library boundaries) which are not part of a
+ * public API.
+ */
+
+#library('date_format_internal');
+#import('intl_helpers.dart');
+
+/**
+ * This holds the symbols to be used for date/time formatting, indexed
+ * by locale. Note that it will be set differently during initialization,
+ * depending on what implementation we are using. By default, it is initialized
+ * to an instance of UninitializedLocaleData, so any attempt to use it will
+ * result in an informative error message.
+ */
+var dateTimeSymbols =
+    const UninitializedLocaleData('initializeDateFormatting(<locale>)');
+
+/**
+ * This holds the patterns used for date/time formatting, indexed
+ * by locale. Note that it will be set differently during initialization,
+ * depending on what implementation we are using. By default, it is initialized
+ * to an instance of UninitializedLocaleData, so any attempt to use it will
+ * result in an informative error message.
+ */
+var dateTimePatterns =
+    const UninitializedLocaleData('initializeDateFormatting(<locale>)');
+
+/**
+ * Initialize the symbols dictionary.

[Emily Fortuna, 2012/09/04 20:14:42]

Can you explain here how "symbols" is expected to work as a function?

[Alan Knight, 2012/09/04 23:39:03]

Done.

+ */
+void initializeDateSymbols(Function symbols) {
+  if (dateTimeSymbols is UninitializedLocaleData) {
+    dateTimeSymbols = symbols();
+  }
+}
+
+/// Initialize the patterns dictionary.

[Emily Fortuna, 2012/09/04 20:14:42]

For sake of consistency, make this comment in the /** */ format like the
function above.

[Alan Knight, 2012/09/04 23:39:03]

Done.

+void initializeDatePatterns(Function patterns) {
+  if (dateTimePatterns is UninitializedLocaleData) {
+    dateTimePatterns = patterns();
+  }
+}
+
+/**

[Emily Fortuna, 2012/09/04 20:14:42]

Either add a comment here or remove the comment notation: /** */

[Alan Knight, 2012/09/04 23:39:03]

Done.

+ */
+Future initializeIndividualLocaleDateFormatting(Function init) {
+  return init(dateTimeSymbols, dateTimePatterns);
+}