From d4593725a470111f6916ed4f6f840ee49580cd84 Mon Sep 17 00:00:00 2001
From: Mike Gerwitz <mike@mikegerwitz.com>
Date: Sun, 14 Nov 2010 21:33:13 -0500
Subject: [PATCH] If a definition is provided for an abstract method, the
 concrete implementation must be compatiable (proper number of arguments)

---
 lib/class.js                | 15 +++++++++++++++
 test/test-class-abstract.js | 26 ++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/lib/class.js b/lib/class.js
index f038213..99acddb 100644
--- a/lib/class.js
+++ b/lib/class.js
@@ -64,6 +64,8 @@ exports.abstractMethod = function( definition )
     };
 
     define_secure_prop( method, 'abstractFlag', true );
+    define_secure_prop( method, 'definition', definition );
+
     return method;
 }
 
@@ -135,6 +137,19 @@ function prop_copy( props, dest, result_data )
                 // then the method should no longer be considered abstract
                 if ( abstract_map[ property ] !== undefined )
                 {
+                    if ( pre.definition )
+                    {
+                        // ensure the concrete definition is compatible with
+                        // that of its supertype
+                        if ( prop.length < pre.definition.length )
+                        {
+                            throw new Error(
+                                "Declaration of " + property + " must be compatiable" +
+                                    "with that of its supertype"
+                            );
+                        }
+                    }
+
                     delete abstract_methods[ abstract_map[ property ] ];
                     abstract_regen = true;
                 }
diff --git a/test/test-class-abstract.js b/test/test-class-abstract.js
index 29e8dfe..56b3706 100644
--- a/test/test-class-abstract.js
+++ b/test/test-class-abstract.js
@@ -158,3 +158,29 @@ assert.equal(
     "Can call constructors of abstract supertypes"
 );
 
+
+assert.throws( function()
+{
+    AbstractFoo.extend(
+    {
+        // incorrect number of arguments
+        method: function()
+        {
+        },
+    });
+}, Error, "Concrete methods must implement the proper number of argments" );
+
+assert.doesNotThrow(
+    function()
+    {
+        AbstractFoo.extend(
+        {
+            second: function( foo )
+            {
+            },
+        });
+    }, Error,
+    "Concrete methods needn't implement the proper number of arguments if " +
+        "no definition was provided"
+);
+