Updated message formatting to be more compatible with Dart string interpolation.

lib/i18n/message_format.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.
  *
- * Message/plural format library with locale support.
+ * Library for internationalizing and localizing user messages, including 
+ * support for customizing them based on plurals and genders.
  *
- * Message format grammar:
- *
- *    messageFormatPattern := string ( "{" messageFormatElement "}" string )*
- *    messageFormatElement := argumentIndex [ "," elementFormat ]
- *    elementFormat := "plural" "," pluralStyle
- *                      | "select" "," selectStyle
- *    pluralStyle :=  pluralFormatPattern
- *    selectStyle :=  selectFormatPattern
- *    pluralFormatPattern := \\[ "offset" ":" offsetIndex ] pluralForms*
- *    selectFormatPattern := pluralForms*
- *    pluralForms := stringKey "{" ( "{" messageFormatElement "}"|string )* "}"
+ * Messages are written as functions with either one parameter (which can omitted).

[Emily Fortuna, 2012/06/02 01:19:26]

add line breaks for 80 char here and below

[Alan Knight, 2012/06/02 02:19:44]

Done.

+ * The function name serves as an identifier for the message, and is customarily 
+ * given a unique prefix such as intl_ to distinguish it from application functions.
+ * The function is expected to return a single interpolated string, based on the 
+ * parameter (which can be a Map or a complex object).
+ * 
+ * For example
+ *   intl_helloWorld () => "Hello world";
+ *   intl_oneValue (waiting) => "There are $waiting jobs waiting";
+ *   intl_dict (dict) => "Hello ${dict['name']}, your waiting time is ${dict['minutes']} minutes";
+ * 
+ * More complex formatting can make use of the Intl object and associated message format.
+ * Here is a more complete example of usage with complex formatting
+ *    var intl = new Intl();
+ *    intl_howManyPeopleAreHere (NUM) 
+ *      //@desc Lists how many people are here 
+ *       => "There ${intl.plural(NUM,{'0': 'are', '1': 'is', 'other': 'are'})} "
+ *          "$NUM other ${intl.plural(NUM, {'1':'person', 'other': 'people'})} here.";

[Emily Fortuna, 2012/06/02 01:19:26]

get rid of tabs in this line and below --> only spaces

[Alan Knight, 2012/06/02 02:19:44]

Done.

+ *       var msg_format = new MessageFormat(intl_howManyPeopleAreHere);
+ *       msg_format.format(2);
  *
  *
- * Message example:
- *
- * I see {NUM_PEOPLE, plural, offset:1
- *         =0 {no one at all}
- *         =1 {{WHO}}
- *         one {{WHO} and one other person}
- *         other {{WHO} and # other people}}
- * in {PLACE}.
- *
- * Calling format({'NUM_PEOPLE': 2, 'WHO': 'Mark', 'PLACE': 'Athens'}) would
- * produce "I see Mark and one other person in Athens." as output.
- *
- * See tests/message_format_test.dart for more examples.
+ * See tests/message_format_test.dart for more comprehensive examples.
  */
 
 #library('MessageFormat');
+#import('intl.dart');
 
 class MessageFormat {
 
   /**
-   * Literal strings, including '', are replaced with \uFDDF_x_ for
-   * parsing purposes, and recovered during format phase.
-   * \uFDDF is a Unicode nonprinting character, not expected to be found in the
-   * typical message.
+   * The message which we are formatting.

[Emily Fortuna, 2012/06/02 01:19:26]

if it's a one line comment, we can shorten it to:
/** The message which we are formatting. */

[Alan Knight, 2012/06/02 02:19:44]

Done.

    */
-  final String _LITERAL_PLACEHOLDER = '\uFDDF_';
-
-  /** String describing the use case for this message.*/
-  final String _messageDescription;
+  Function _messageFunction;
 
   /**
-   * String that is used to determin the particular case and gender needed to be
-   * returned. The format of this string follows the same pattern as in Closure,
-   * Java, and C++. This pattern is described at the beginning of this class
-   * definition. See tests/message_format_test.dart for more examples.
+   * Constructors. Can take a particular message, or have that left open.
    */
-  final String _messageFunction;
+  MessageFormat.on(this._messageFunction);

[Emily Fortuna, 2012/06/02 01:19:26]

My impression so far is Dart is much more likely to take optional parameters
than named constructors. 

[Alan Knight, 2012/06/02 02:19:44]

Changed to an optional parameter

+  MessageFormat();
 
   /**
-   * Constructor. Accepts a String [_messageDescription] describing the use case
-   * for this string in the program, and a the String [_messageFunction] that is
-   * used to determine the particular case and gender for the given instance.
+   * Formats a message and returns the correctly formatted message in the desired language.
+   * There are two versions, one which assumes we were constructed with a particular message
+   *  and one where the message is passed in as an argument.

[Emily Fortuna, 2012/06/02 01:19:26]

comments please explaining what messageParameters is

[Alan Knight, 2012/06/02 02:19:44]

Done.

    */
-  const MessageFormat(this._messageDescription, this._messageFunction);
 
-  /**
-   * Formats a message. By default, we treat '#' with special meaning
-   * representing the number (plural_variable - plural_offset). If [ignorePound]
-   * is true, then we do not treat '#' as a special character, and it is just
-   * treated literally. [namedParameters] is a map of String keys to String or
-   * int values to influence the formatting of the message or data in the
-   * message. For example, example, in the call to 
-   *     msg_formatter.format({'NUM_PEOPLE': 5, 'NAME': 'Angela'}),
-   * object \{'NUM_PEOPLE': 5, 'NAME': 'Angela'\} holds positional parameters.
-   * 1st parameter could mean 5 people, which could influence plural format,
-   * and 2nd parameter is just relevant data to be printed out in the proper
-   * position in the message.
-   * Returns the correctly formatted message in the desired language.
-   */
-  String format(Map<String, dynamic> messageParameters,
-                [bool ignorePound=false]) {
-    // TODO(efortuna): actually perform the translation here. For now, I'm just
-    // returning a description of the message to be returned.
-    return _messageDescription;
+  String format(var messageParameters) {
+    return _messageFunction(messageParameters);
   }
+
+  String formatMessage(Function messageFunction,var messageParameters) {

[Emily Fortuna, 2012/06/02 01:19:26]

comments please?

+    if (messageParameters == null) {
+       return messageFunction();
+    } else {
+       return messageFunction(messageParameters);
+    }
+  }
+
+
 }