a === b -> identical(a, b)

samples/swarm/swarm_ui_lib/touch/TouchHandler.dart

 // Copyright (c) 2011, 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.
 
 /**
  * Touch Handler. Class that handles all touch events and
  * uses them to interpret higher level gestures and behaviors. TouchEvent is a
  * built in mobile safari type:
  * [http://developer.apple.com/safari/library/documentation/UserExperience/Reference/TouchEventClassReference/TouchEvent/TouchEvent.html].
  *
@@ skipping 215 matching lines @@
   bool isTracking() {
     return _tracking;
   }
 
   /**
    * Touch end handler.
    */
   void _onEnd(int timeStamp, [TouchEvent e = null]) {
     _touching = false;
     _touchable.onTouchEnd();
-    if (!_tracking || _draggable === null) {
+    if (!_tracking || _draggable == null) {
       return;
     }
     Touch touch = _getLastTouch();
     int clientX = touch.clientX;
     int clientY = touch.clientY;
     if (_dragging) {
       _endTime = timeStamp;
       _endTouchX = clientX;
       _endTouchY = clientY;
       _recentTouchesX = _removeOldTouches(_recentTouchesX, timeStamp);
       _recentTouchesY = _removeOldTouches(_recentTouchesY, timeStamp);
       _draggable.onDragEnd();
-      if (e !== null) {
+      if (e != null) {
         e.preventDefault();
       }
       ClickBuster.preventGhostClick(_startTouchX, _startTouchY);
     }
     _endTracking();
   }
 
   /**
    * Touch move handler.
    */
   void _onMove(TouchEvent e) {
-    if (!_tracking || _draggable === null) {
+    if (!_tracking || _draggable == null) {
       return;
     }
     final touch = e.touches[0];
     int clientX = touch.clientX;
     int clientY = touch.clientY;
     int moveX = _lastTouchX - clientX;
     int moveY = _lastTouchY - clientY;
     _totalMoveX += moveX.abs();
     _totalMoveY += moveY.abs();
     _lastTouchX = clientX;
@@ skipping 31 matching lines @@
   }
 
   /**
    * Touch start handler.
    */
   void _onStart(TouchEvent e) {
     if (_touching) {
       return;
     }
     _touching = true;
-    if (!_touchable.onTouchStart(e) || _draggable === null) {
+    if (!_touchable.onTouchStart(e) || _draggable == null) {
       return;
     }
     final touch = e.touches[0];
     _startTouchX = _lastTouchX = touch.clientX;
     _startTouchY = _lastTouchY = touch.clientY;
     _startTime = e.timeStamp;
     // TODO(jacobr): why don't we just clear the lists?
     _recentTouchesX = new List<int>();
     _recentTouchesY = new List<int>();
     _recentTouchesX.add(touch.clientX);
@@ skipping 39 matching lines @@
   List<int> _removeTouchesInWrongDirection(List<int> recentTouches,
                                             int lastMove, int recentMove) {
     if (lastMove !=0 && recentMove != 0 && recentTouches.length > 2 &&
         _xor(lastMove > 0, recentMove > 0)) {
       return _removeFirstN(recentTouches, recentTouches.length - 2);
     }
     return recentTouches;
   }
 
   // TODO(jacobr): why doesn't bool implement the xor operator directly?
-  static bool _xor(bool a, bool b) {
-    return (a === true || b === true) && !(a === true && b === true);
-  }
+  static bool _xor(bool a, bool b) => a != b;

[Lasse Reichstein Nielsen, 2012/11/12 13:10:41]

Are we sure this isn't an attempt to do boolify on incoming non-bool values in
unchecked mode?
If we are, then consider just inlining this.

[floitsch, 2012/11/12 22:18:43]

Afaics the only use is in line 366. Not inlining, since "xor" may reflect better
the purpose.

 
   /**
    * Reset the touchable element.
    */
   void reset() {
     _endTracking();
     _touching = false;
   }
 
   /**
    * Call this method to enable drag behavior on a draggable delegate.
    * The [draggable] object can be the same as the [_touchable] object, they are
    * assigned to different members to allow for strong typing with interfaces.
    */
   void setDraggable(Draggable draggable) {
     _draggable = draggable;
   }
 }