From e03d5861bbc3f203a8d250dd1643b4608ffd0a1d Mon Sep 17 00:00:00 2001
From: Mike Gerwitz <mike@mikegerwitz.com>
Date: Fri, 21 Jan 2011 22:19:22 -0500
Subject: [PATCH] Overridden methods must have >= length parameter lists

---
 lib/member_builder.js              |  9 +++++++++
 test/test-member_builder-method.js | 28 ++++++++++++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/lib/member_builder.js b/lib/member_builder.js
index decca44..891d9a7 100644
--- a/lib/member_builder.js
+++ b/lib/member_builder.js
@@ -73,6 +73,15 @@ exports.buildMethod = function( members, meta, name, value, keywords )
         );
     }
 
+    // ensure parameter list is at least the length of its supertype
+    if ( prev && (value.length < prev.length ) )
+    {
+        throw new TypeError(
+            "Declaration of method '" + name + "' must be compatiable " +
+                "with that of its supertype"
+        );
+    }
+
     getMemberVisibility( members, keywords )[ name ] = value;
 };
 
diff --git a/test/test-member_builder-method.js b/test/test-member_builder-method.js
index 69feefa..fabe858 100644
--- a/test/test-member_builder-method.js
+++ b/test/test-member_builder-method.js
@@ -61,3 +61,31 @@ mb_common.assertCommon();
     }, TypeError, "Cannot override property with method" );
 } )();
 
+
+/**
+ * To ensure interfaces of subtypes remain compatible with that of their
+ * supertypes, the parameter lists must match and build upon each other.
+ */
+( function testMethodOverridesMustHaveEqualOrGreaterParameters()
+{
+    mb_common.value = function( one, two ) {};
+    mb_common.buildMemberQuick();
+
+    assert.doesNotThrow( function()
+    {
+        mb_common.buildMemberQuick( {}, true );
+    }, TypeError, "Method can have equal number of parameters" );
+
+    assert.doesNotThrow( function()
+    {
+        mb_common.value = function( one, two, three ) {};
+        mb_common.buildMemberQuick( {}, true );
+    }, TypeError, "Method can have greater number of parameters" );
+
+    assert.throws( function()
+    {
+        mb_common.value = function( one ) {};
+        mb_common.buildMemberQuick( {}, true );
+    }, TypeError, "Method cannot have lesser number of parameters" );
+} )();
+