Refactor Date.

corelib/src/date.dart

Index: corelib/src/date.dart
diff --git a/corelib/src/date.dart b/corelib/src/date.dart
index c3da9d00d9475a8a512db2082e81c47ea26766b1..4a7c667cbdb0fb53bfd64b423964b4777ffae461 100644
--- a/corelib/src/date.dart
+++ b/corelib/src/date.dart
@@ -5,6 +5,21 @@
 // Dart core library.
 
 /**
+ * Returns the local time-zone as defined in the official zone.tab file.
+ *
+ * Examples: [:"Europe/Andorra":], [:"America/Los_Angeles":] or
+ * [:"Europe/Paris":].
+ *
+ * If the underlying implementation is unable to get the timezone string
+ * returns the offset to UTC prefixed with "GMT". Examples: [:"GMT+03":],
+ * [:"GMT-02":], or [:"GTM+04:30":].
+ */
+String get timeZoneName() => DateImplementation.timeZoneName();
+
+/** Returns the current local time-zone's offset to UTC. */
+Duration get timeZoneOffset() => DateImplementation.timeZoneOffset();
+
+/**
  * Date is the public interface to a point in time.
  */
 interface Date extends Comparable, Hashable default DateImplementation {
@@ -47,21 +62,8 @@ interface Date extends Comparable, Hashable default DateImplementation {
         int milliseconds]);
 
   /**
-   * Constructs a [Date] instance based on the individual parts.
-   * [timeZone] may not be [:null:].
-   */
-  Date.withTimeZone(int year,
-                    int month,
-                    int day,
-                    int hours,
-                    int minutes,
-                    int seconds,
-                    int milliseconds,
-                    TimeZone timeZone);
-
-  /**
-   * Constructs a new [Date] instance with current date time value.
-   * The [timeZone] of this instance is set to the local time-zone.
+   * Constructs a new [Date] instance with current date time value in the
+   * local time-zone.
    */
   Date.now();
 
@@ -71,16 +73,15 @@ interface Date extends Comparable, Hashable default DateImplementation {
   Date.fromString(String formattedString);
 
   /**
-   * Constructs a new [Date] instance with the given time zone. The given
-   * [timeZone] must not be [:null:].
+   * Constructs a new [Date] instance in the local time-zone.
    *
    * This constructor is the only one that doesn't need to be computations and
    * which can therefore be [:const:].
    *
    * The constructed [Date] represents 1970-01-01T00:00:00Z + [value]ms in
-   * the given [timeZone].
+   * the local time-zone.
    */
-  const Date.fromEpoch(int value, TimeZone timeZone);
+  const Date.fromEpoch(int value);
 
   /**
    * Returns true if [this] occurs before [other]. The comparison is independent
@@ -104,15 +105,6 @@ interface Date extends Comparable, Hashable default DateImplementation {
   bool operator >=(Date other);
 
   /**
-   * Returns a new [Date] in the given [targetTimeZone] time zone. The
-   * [value] of the new instance is equal to [:this.value:].
-   *
-   * This call is equivalent to
-   *  [:new Date.fromEpoch(this.value, targetTimeZone):].
-   */
-  Date changeTimeZone(TimeZone targetTimeZone);
-
-  /**
    * Returns the year.
    */
   int get year();
@@ -155,31 +147,22 @@ interface Date extends Comparable, Hashable default DateImplementation {
   /**
    * Returns milliseconds from 1970-01-01T00:00:00Z (UTC).
    *
-   * Note that this value is independent of [timeZone].
+   * Note that this value is independent of any time-zone.
    */
   final int value;
 
   /**
-   * Returns the timeZone of this instance.
-   */
-  final TimeZone timeZone;
-
-  /**
-   * Returns true if this [Date] is set to local time.
-   */
-  bool isLocalTime();
-
-  /**
-   * Returns true if this [Date] is set to UTC time.
-   * This is equivalent to [:this.timeZone.isUtc():].
+   * Returns a human readable string for this instance. The returned string
+   * is constructed in the local time-zone and does not have any time-zone
+   * indication. Example: [:2012-05-14 14:20:25.442:]
    */
-  bool isUtc();
+  String toString();
 
   /**
-   * Returns a human readable string for this instance.
-   * The returned string is constructed for the [timeZone] of this instance.
-   */
-  String toString();
+  * Returns a human readable string for this instance in UTC time-zone.
+  * Example: [:2012-05-14 12:21:04.989Z:]
+  */
+  String toUtcString();
 
   /**
    * Returns a new [Date] with the [duration] added to this instance.