From a083313538f912b690b31585a7496bca19390db6 Mon Sep 17 00:00:00 2001
From: Mike Gerwitz <mike@mikegerwitz.com>
Date: Sun, 14 Nov 2010 00:47:27 -0500
Subject: [PATCH] Began implementing abstract methods

---
 lib/class.js                | 22 ++++++++++++++++++++++
 test/test-class-abstract.js | 10 ++++++++++
 2 files changed, 32 insertions(+)

diff --git a/lib/class.js b/lib/class.js
index ca46b5d..1760911 100644
--- a/lib/class.js
+++ b/lib/class.js
@@ -43,6 +43,28 @@ exports.extend = function( base )
 }
 
 
+/**
+ * Creates an abstract method
+ *
+ * Abstract methods must be implemented by a subclass and cannot be called
+ * directly. If a class contains a single abstract method, the class itself is
+ * considered to be abstract and cannot be instantiated. It may only be
+ * extended.
+ *
+ * @param  {Function}  definition  function definition that concrete
+ *                                 implementations must follow
+ *
+ * @return  {Function}
+ */
+exports.abstractMethod = function( definition )
+{
+    return function()
+    {
+        throw new Error( "Cannot call abstract method" );
+    }
+}
+
+
 /**
  * Default class implementation
  *
diff --git a/test/test-class-abstract.js b/test/test-class-abstract.js
index e2322d1..cae1c17 100644
--- a/test/test-class-abstract.js
+++ b/test/test-class-abstract.js
@@ -66,6 +66,16 @@ var ConcreteFoo = AbstractFoo.extend(
     },
 });
 
+assert.ok(
+    ( abstractMethod() instanceof Function ),
+    "abstractMethod() returns a function"
+);
+
+assert.throws( function()
+{
+    abstractMethod()();
+}, Error, "Abstract methods cannot be called" );
+
 assert.ok(
     ( Foo.isAbstract instanceof Function ),
     "All classes should have an isAbstract() method"