Implement 'as' operator.

corelib/src/exceptions.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.
 
 // Exceptions are thrown either by the VM or from Dart code.
 
 /**
  * Interface implemented by all core library exceptions.
  */
 interface Exception default ExceptionImplementation {
@@ skipping 20 matching lines @@
 }
 
 
 /**
  * Exception thrown because of non-existing receiver's method.
  */
 class NoSuchMethodException implements Exception {
   const NoSuchMethodException(Object this._receiver,
                               String this._functionName,
                               List this._arguments,
-                              [List existingArgumentNames = null]) : 
+                              [List existingArgumentNames = null]) :
                                 this._existingArgumentNames = existingArgumentNames;

[floitsch, 2012/06/25 18:21:09]

not your code, but 80chars.

[Lasse Reichstein Nielsen, 2012/06/26 08:26:03]

Done.

 
   String toString() {
     StringBuffer sb = new StringBuffer();
     for (int i = 0; i < _arguments.length; i++) {
       if (i > 0) {
         sb.add(", ");
       }
       sb.add(_arguments[i]);
     }
     if (_existingArgumentNames === null) {
@@ skipping 80 matching lines @@
     }
   }
 
   String get exceptionName() => "NullPointerException";
 
   final String functionName;
   final List arguments;
 }
 
 
+class CastException implements Exception {
+  // TODO(lrn): Change actualType and expectedType to "Type" when reified
+  // types are available.
+  final Object actualType;
+  final Object expectedType;
+
+  CastException(this.actualType, this.expectedType);
+  String toString() {
+    return "$exceptionName: Casting value of type $actualType to"
+           " incompatible type $expectedType";
+  }
+
+  String get exceptionName() => "CastException";
+}
+
+
 class NoMoreElementsException implements Exception {
   const NoMoreElementsException();
   String toString() => "NoMoreElementsException";
 }
 
 
 class EmptyQueueException implements Exception {
   const EmptyQueueException();
   String toString() => "EmptyQueueException";
 }
@@ skipping 20 matching lines @@
   String toString() => "IllegalJSRegExpException: '$_pattern' '$_errmsg'";
   final String _pattern;
   final String _errmsg;
 }
 
 
 class IntegerDivisionByZeroException implements Exception {
   const IntegerDivisionByZeroException();
   String toString() => "IntegerDivisionByZeroException";
 }