From e3c526b89d00157b95ac1efda81aafbe20cc1027 Mon Sep 17 00:00:00 2001
From: Mike Gerwitz <mike@mikegerwitz.com>
Date: Wed, 13 Apr 2011 23:06:24 -0400
Subject: [PATCH] Writes to public static properties now work properly

---
 lib/class_builder.js              | 33 ++++++++++++++++----
 test/test-class_builder-static.js | 50 ++++++++++++++++++++++++++++++-
 2 files changed, 76 insertions(+), 7 deletions(-)

diff --git a/lib/class_builder.js b/lib/class_builder.js
index 8058fd0..d78a32b 100644
--- a/lib/class_builder.js
+++ b/lib/class_builder.js
@@ -614,13 +614,34 @@ function attachStatic( ctor, members, base, inheriting )
     {
         ctor.___$$sprops$$ = props;
 
-        ctor.$ = function( prop )
+        // provide a method to access static properties
+        ctor.$ = function( prop, val )
         {
-            // attempt to return property if it is our own, otherwise look up on
-            // parent (the parent will look up its parent as well, if necessary)
-            return props[ 'public' ][ prop ]
-                || base.$( prop )
-            ;
+            // we use hasOwnProperty to ensure that undefined values will not
+            // cause us to continue checking the parent, thereby potentially
+            // failing to set perfectly legal values
+            var has = Object.prototype.hasOwnProperty.call(
+                props[ 'public' ], prop
+            );
+
+            // if we don't own the property, let the parent(s) handle it
+            if ( !has )
+            {
+                return base.$.apply( this, arguments );
+            }
+
+            // if a value was provided, this method should be treated as a
+            // setter rather than a getter
+            if ( val )
+            {
+                props[ 'public' ][ prop ] = val;
+                return;
+            }
+            else
+            {
+                // return the value
+                return props[ 'public' ][ prop ];
+            }
         };
     }
 
diff --git a/test/test-class_builder-static.js b/test/test-class_builder-static.js
index 7511973..ae82a63 100644
--- a/test/test-class_builder-static.js
+++ b/test/test-class_builder-static.js
@@ -308,7 +308,9 @@ var common    = require( './common' ),
  */
 ( function testPublicStaticPropertyReferencesAreInheritedBySubtypes()
 {
-    var val = [ 1, 2, 3 ],
+    var val  = [ 1, 2, 3 ],
+        val2 = [ 'a', 'b', 'c' ],
+
         Foo = builder.build(
         {
             'public static bar': val,
@@ -320,5 +322,51 @@ var common    = require( './common' ),
     assert.ok( SubFoo.$('bar') === Foo.$('bar'),
         "Inherited static properties should share references"
     );
+
+    // setting a property on Foo should set the property on SubFoo and
+    // vice-versa
+    Foo.$( 'bar', val2 );
+    assert.deepEqual( Foo.$( 'bar' ), val2,
+        "Can set static property values"
+    );
+
+    assert.ok( Foo.$( 'bar' ) === SubFoo.$( 'bar' ),
+        "Setting a static property value on a supertype also sets the value " +
+            "on subtypes"
+    );
+
+    SubFoo.$( 'bar', val );
+    assert.ok( Foo.$( 'bar' ) === SubFoo.$( 'bar' ) );
+} )();
+
+
+/**
+ * Static members do not have the benefit of prototype chains. We must
+ * implement our own means of traversing the inheritance tree. This is done by
+ * checking to see if a class has defined the requested property, then
+ * forwarding the call to the parent if it has not.
+ *
+ * The process of looking up the property is very important. hasOwnProperty is
+ * used rather than checking for undefined, because they have drastically
+ * different results. Setting a value to undefined (if hasOwnProperty were not
+ * used) would effectively forward all requests to the base class (since no
+ * property would be found), thereby preventing it from ever being written to
+ * again.
+ */
+( function testSettingsStaticPropertiesToUndefinedWillNotCorruptLookupProcess()
+{
+    var val = 'baz',
+        Foo = builder.build(
+        {
+            'public static foo': '',
+        } )
+    ;
+
+    Foo.$( 'foo', undefined );
+    Foo.$( 'foo', val );
+
+    assert.equal( Foo.$( 'foo' ), val,
+        "Setting static property to undefined does not corrupt lookup process"
+    );
 } )();