Cleanup VM error handling.

runtime/lib/error.dart

Index: runtime/lib/error.dart
diff --git a/runtime/lib/error.dart b/runtime/lib/error.dart
index acac03599089dc549bbbef96e8f2fa8c8ea49ca4..10ed6e0cdd14550c5bbffcb36e4eb4391ac1565f 100644
--- a/runtime/lib/error.dart
+++ b/runtime/lib/error.dart
@@ -4,15 +4,15 @@
 // Errors are created and thrown by DartVM only.
 // Changes here should also be reflected in corelib/error.dart as well
 
-class AssertionErrorImplementation extends AssertionError {
-  factory AssertionErrorImplementation._uninstantiable() {
-    throw new UnsupportedError(
-        "AssertionError can only be allocated by the VM");
-  }
+class _AssertionErrorImplementation extends AssertionError {
+  _AssertionErrorImplementation(
+    this.failedAssertion, this.url, this.line, this.column);
+
   static _throwNew(int assertionStart, int assertionEnd)
       native "AssertionError_throwNew";
+
   String toString() {
-    return "'$url': Failed assertion: line $line pos $column: "
+    return "'$url': Failed assertion: line $line pos $_column: "
         "'$failedAssertion' is not true.";
   }
   final String failedAssertion;
@@ -21,21 +21,24 @@ class AssertionErrorImplementation extends AssertionError {
   final int column;
 }
 
-class TypeErrorImplementation
-    extends AssertionErrorImplementation
+class _TypeErrorImplementation
+    extends _AssertionErrorImplementation
     implements TypeError {
-  factory TypeErrorImplementation._uninstantiable() {
-    throw new UnsupportedError(
-        "TypeError can only be allocated by the VM");
-  }
+
+  _TypeErrorImplementation(
+    String failedAssertion, String url, int line, int column,
+    this.srcType, this.dstType, this.dstName, this._malformedError)
+      : super(failedAssertion, url, line, column);
+
   static _throwNew(int location,
                    Object src_value,
                    String dst_type_name,
                    String dst_name,
                    String malformed_error)
       native "TypeError_throwNew";
+
   String toString() {
-    String str = (malformedError != null) ? malformedError : "";
+    String str = (_malformedError != null) ? _malformedError : "";
     if ((dstName != null) && (dstName.length > 0)) {
       str = "${str}type '$srcType' is not a subtype of "
             "type '$dstType' of '$dstName'.";
@@ -44,23 +47,27 @@ class TypeErrorImplementation
     }
     return str;
   }
+
   final String srcType;
   final String dstType;
   final String dstName;
-  final String malformedError;
+  final String _malformedError;
 }
 
-class CastErrorImplementation
-    extends TypeErrorImplementation
+class _CastErrorImplementation
+    extends _TypeErrorImplementation
     implements CastError {
-  factory CastErrorImplementation._uninstantiable() {
-    throw new UnsupportedError(
-        "CastError can only be allocated by the VM");
-  }
+
+  _CastErrorImplementation(
+    String failedAssertion, String url, int line, int column,
+    String srcType, String dstType, String dstName, String malformedError)
+      : super(failedAssertion, url, line, column,
+              srcType, dstType, dstName, malformedError);
+
   // A CastError is allocated by TypeError._throwNew() when dst_name equals
   // Exceptions::kCastErrorDstName.
   String toString() {
-    String str = (malformedError != null) ? malformedError : "";
+    String str = (_malformedError != null) ? _malformedError : "";
     if ((dstName != null) && (dstName.length > 0)) {
       str = "${str}type '$srcType' is not a subtype of "
             "type '$dstType' in type cast.";
@@ -71,43 +78,44 @@ class CastErrorImplementation
   }
 }
 
-class FallThroughErrorImplementation extends FallThroughError {
-  factory FallThroughErrorImplementation._uninstantiable() {
-    throw new UnsupportedError(
-        "FallThroughError can only be allocated by the VM");
-  }
+class _FallThroughErrorImplementation extends FallThroughError {
+
+  _FallThroughErrorImplementation(this._url, this._line);
+
   static _throwNew(int case_clause_pos) native "FallThroughError_throwNew";
+
   String toString() {
-    return "'$url': Switch case fall-through at line $line.";
+    return "'$_url': Switch case fall-through at line $_line.";
   }
-  final String url;
-  final int line;
+
+  final String _url;
+  final int _line;
 }
 
-class InternalError {
-  const InternalError(this._msg);
+class _InternalError {
+  const _InternalError(this._msg);
   String toString() => "InternalError: '${_msg}'";
   final String _msg;
 }
 
 
-class AbstractClassInstantiationErrorImplementation
+class _AbstractClassInstantiationErrorImplementation
     extends AbstractClassInstantiationError {
 
-  factory AbstractClassInstantiationErrorImplementation._uninstantiable() {
-    throw new UnsupportedError(
-        "AbstractClassInstantiationError can only be allocated by the VM");
-  }
+  _AbstractClassInstantiationErrorImplementation(
+      String className, this._url, this._line)
+      : this._className = className,
+        super(className);
 
   static _throwNew(int case_clause_pos, String className)
       native "AbstractClassInstantiationError_throwNew";
 
   String toString() {
-    return "Cannot instantiate abstract class $className: "
-           "url '$url' line $line";
+    return "Cannot instantiate abstract class $_className: "
+           "_url '$_url' line $_line";
   }
 
-  final String className;
-  final String url;
-  final int line;
+  final String _className;

[siva, 2013/07/12 16:49:36]

The className field already exists in the super class why repeat it here?

[floitsch, 2013/07/12 17:12:36]

done.

+  final String _url;
+  final int _line;

[siva, 2013/07/12 16:49:36]

If we are going with this scheme of using a Dart constructor then why not stream
line it some more by hoisting the url and line fields  up to "class Error" as
almost all error classes seem to declare these fields.

[floitsch, 2013/07/12 17:12:36]

Sure. We can discuss this.
Not in this CL, though.

 }