From 2e930482d27c3fa31d614d3bad028c6fa788e652 Mon Sep 17 00:00:00 2001
From: Mike Gerwitz <mike@mikegerwitz.com>
Date: Wed, 1 Dec 2010 21:34:57 -0500
Subject: [PATCH] Abstract methods of subtypes overriding abstract methods must
 be compatiable with the previous definition

---
 lib/util.js                 | 23 +++++++++++++++--------
 test/test-class-abstract.js | 24 ++++++++++++++++++++++++
 2 files changed, 39 insertions(+), 8 deletions(-)

diff --git a/lib/util.js b/lib/util.js
index 7ef5600..323a55f 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -255,17 +255,19 @@ function method_override(
         throw new TypeError( "Cannot override method with non-method" );
     }
 
-    // if we were given a concrete method to an abstract method,
-    // then the method should no longer be considered abstract
-    if ( ( abstract_map[ name ] !== undefined )
-        && ( exports.isAbstractMethod( new_method.abstractFlag ) === false )
-    )
+    if ( abstract_map[ name ] !== undefined )
     {
+        var is_abstract = exports.isAbstractMethod( new_method );
+
         if ( super_method.definition instanceof Array )
         {
+            var arg_len = ( is_abstract )
+                ? new_method.definition.length
+                : new_method.length;
+
             // ensure the concrete definition is compatible with
             // that of its supertype
-            if ( new_method.length < super_method.definition.length )
+            if ( arg_len < super_method.definition.length )
             {
                 throw new Error(
                     "Declaration of " + name + " must be compatiable" +
@@ -274,8 +276,13 @@ function method_override(
             }
         }
 
-        delete abstract_methods[ abstract_map[ name ] ];
-        data.abstractModified = true;
+        // if this was a concrete method, then it should no longer be marked as
+        // abstract
+        if ( is_abstract === false )
+        {
+            delete abstract_methods[ abstract_map[ name ] ];
+            data.abstractModified = true;
+        }
     }
 
     // this is the method that will be invoked when the requested
diff --git a/test/test-class-abstract.js b/test/test-class-abstract.js
index 96c84f6..98ebd59 100644
--- a/test/test-class-abstract.js
+++ b/test/test-class-abstract.js
@@ -172,6 +172,30 @@ assert.throws( function()
     });
 }, Error, "Concrete methods must implement the proper number of argments" );
 
+assert.throws( function()
+{
+    AbstractFoo.extend(
+    {
+        // incorrect number of arguments
+        method: abstractMethod(),
+    });
+}, Error, "Abstract methods of subtypes must implement the proper number of argments" );
+
+assert.doesNotThrow(
+    function()
+    {
+        AbstractFoo.extend(
+        {
+            // incorrect number of arguments
+            method: abstractMethod( 'one', 'two', 'three', 'four' ),
+        });
+    },
+    Error,
+    "Abstract methods of subtypes may implement additional arguments, so long" +
+        "as they implement at least the required number of arguments as defined by " +
+        "it supertype"
+);
+
 assert.doesNotThrow(
     function()
     {