Can no longer override non-virtual methods (#19)

lib/member_builder.js

@@ -183,6 +183,14 @@ function validateMethod( keywords, prev_data, prev_keywords, value, name )
             );
         }
 
+        // disallow overriding non-virtual methods
+        if ( keywords[ 'override' ] && !( prev_keywords[ 'virtual' ] ) )
+        {
+            throw TypeError(
+                "Cannot override non-virtual method '" + name + "'"
+            );
+        }
+
         // do not allow overriding concrete methods with abstract
         if ( keywords[ 'abstract' ] && !( util.isAbstractMethod( prev ) ) )
         {

test/test-class-extend.js

@@ -401,3 +401,35 @@ for ( var i = 0; i < class_count; i++ )
     );
 } )();
 
+
+/**
+ * Only virtual methods may be overridden.
+ */
+( function testCannotOverrideNonVirtualMethod()
+{
+    try
+    {
+        var Foo = Class(
+            {
+                // non-virtual
+                'public foo': function() {},
+            } ),
+
+            SubFoo = Foo.extend(
+            {
+                // should fail (cannot override non-virtual method)
+                'override public foo': function() {},
+            } );
+    }
+    catch ( e )
+    {
+        assert.ok( e.message.search( 'foo' ),
+            "Non-virtual override error message should contain name of method"
+        );
+
+        return;
+    }
+
+    assert.fail( "Should not be permitted to override non-virtual method" );
+} )();
+

test/test-class-implement.js

@@ -171,8 +171,8 @@ var Type = Interface.extend( {
     // concrete implementation so that we can instantiate it
     var ConcreteFoo = Foo.extend(
         {
-            'override foo':  function() {},
+            'foo':  function() {},
-            'override foo2': function() {},
+            'foo2': function() {},
         }),
 
         concrete_inst = ConcreteFoo()

test/test-member_builder-method.js

@@ -145,7 +145,8 @@ mb_common.assertCommon();
 
 /**
  * Abstract members exist to be overridden. As such, they should be considered
- * virtual.
+ * virtual. In addition, we should be able to override them WITHOUT the override
+ * keyword, since no concrete implementation was previously provided.
  */
 ( function testAbstractMethodsAreConsideredVirtual()
 {
@@ -153,10 +154,10 @@ mb_common.assertCommon();
     mb_common.value = function() {};
     mb_common.buildMemberQuick( { 'abstract': true } );
 
-    // we should be able to override it
+    // we should be able to override it without the override keyword
     assert.doesNotThrow( function()
     {
-        mb_common.buildMemberQuick( { 'override': true }, true );
+        mb_common.buildMemberQuick( {}, true );
     }, Error, "Can overrde abstract methods" );
 } )();
 
@@ -200,13 +201,19 @@ mb_common.assertCommon();
 
     assert.doesNotThrow( function()
     {
-        mb_common.buildMemberQuick( { 'override': true }, true );
+        mb_common.buildMemberQuick(
+            { 'virtual': true, 'override': true },
+            true
+        );
     }, TypeError, "Method can have equal number of parameters" );
 
     assert.doesNotThrow( function()
     {
         mb_common.value = function( one, two, three ) {};
-        mb_common.buildMemberQuick( { 'override': true }, true );
+        mb_common.buildMemberQuick(
+            { 'virtual': true, 'override': true },
+            true
+        );
     }, TypeError, "Method can have greater number of parameters" );
 
     assert.throws( function()