Class.use now creates its own class

lib/ClassBuilder.js

@@ -298,6 +298,7 @@ exports.prototype.build = function extend( _, __ )
         base      = args.pop() || exports.ClassBase,
         prototype = this._getBase( base ),
         cname     = '',
+        autoa     = false,
 
         prop_init      = this._memberBuilder.initMembers(),
         members        = this._memberBuilder.initMembers( prototype ),
@@ -331,6 +332,12 @@ exports.prototype.build = function extend( _, __ )
         delete props.__name;
     }
 
+    // gobble up auto-abstract flag if present
+    if ( ( autoa = props.___$$auto$abstract$$ ) !== undefined )
+    {
+        delete props.___$$auto$abstract$$;
+    }
+
     // IE has problems with toString()
     if ( enum_bug )
     {
@@ -401,8 +408,7 @@ exports.prototype.build = function extend( _, __ )
     new_class.___$$sinit$$          = staticInit;
 
     attachFlags( new_class, props );
-
+    validateAbstract( new_class, cname, abstract_methods, autoa );
-    validateAbstract( new_class, cname, abstract_methods );
 
     // We reduce the overall cost of this definition by defining it on the
     // prototype rather than during instantiation. While this does increase the
@@ -588,13 +594,20 @@ exports.prototype.buildMembers = function buildMembers(
 /**
  * Validates abstract class requirements
  *
+ * We permit an `auto' flag for internal use only that will cause the
+ * abstract flag to be automatically set if the class should be marked as
+ * abstract, instead of throwing an error; this should be used sparingly and
+ * never exposed via a public API (for explicit use), as it goes against the
+ * self-documentation philosophy.
+ *
  * @param  {function()}  ctor              class
  * @param  {string}      cname             class name
  * @param  {{__length}}  abstract_methods  object containing abstract methods
+ * @param  {boolean}     auto              automatically flag as abstract
  *
  * @return  {undefined}
  */
-function validateAbstract( ctor, cname, abstract_methods )
+function validateAbstract( ctor, cname, abstract_methods, auto )
 {
     if ( ctor.___$$abstract$$ )
     {
@@ -606,17 +619,20 @@ function validateAbstract( ctor, cname, abstract_methods )
             );
         }
     }
-    else
+    else if ( abstract_methods.__length > 0 )
     {
-        if ( abstract_methods.__length > 0 )
+        if ( auto )
         {
+            ctor.___$$abstract$$ = true;
+            return;
+        }
+
         throw TypeError(
             "Class " + ( cname || "(anonymous)" ) + " contains abstract " +
             "members and must therefore be declared abstract"
         );
     }
 }
-}
 
 
 /**

lib/Trait.js

@@ -109,9 +109,9 @@ Trait.extend = function( dfn )
     }
 
     // invoked to trigger mixin
-    TraitType.__mixin = function( dfn )
+    TraitType.__mixin = function( dfn, tc )
     {
-        mixin( TraitType, dfn );
+        mixin( TraitType, dfn, tc );
     };
 
     return TraitType;
@@ -238,21 +238,25 @@ function createVirtProxy( acls, dfn )
 /**
  * Mix trait into the given definition
  *
- * The original object DFN is modified; it is not cloned.
+ * The original object DFN is modified; it is not cloned. TC should be
+ * initialized to an empty array; it is used to store context data for
+ * mixing in traits and will be encapsulated within a ctor closure (and thus
+ * will remain in memory).
  *
  * @param  {Trait}   trait  trait to mix in
  * @param  {Object}  dfn    definition object to merge into
+ * @param  {Array}   tc     trait class context
  *
  * @return  {Object}  dfn
  */
-function mixin( trait, dfn )
+function mixin( trait, dfn, tc )
 {
     // the abstract class hidden within the trait
     var acls    = trait.__acls,
         methods = acls.___$$methods$$;
 
     // retrieve the private member name that will contain this trait object
-    var iname = addTraitInst( trait, dfn );
+    var iname = addTraitInst( trait, dfn, tc );
 
     mixMethods( methods['public'], dfn, 'public', iname );
     mixMethods( methods['protected'], dfn, 'protected', iname );
@@ -334,13 +338,13 @@ function mixMethods( src, dest, vis, iname )
  *
  * @param  {Class}   T    trait
  * @param  {Object}  dfn  definition object of class being mixed into
+ * @param  {Array}   tc   trait class object
  *
  * @return  {string}  private member into which C instance shall be stored
  */
-function addTraitInst( T, dfn )
+function addTraitInst( T, dfn, tc )
 {
-    var tc    = ( dfn.___$$tc$$ = ( dfn.___$$tc$$ || [] ) ),
+    var iname = '___$to$' + T.__acls.__cid;
-        iname = '___$to$' + T.__acls.__cid;
 
     // the trait object array will contain two values: the destination field
     // and the trait to instantiate

lib/class.js

@@ -379,24 +379,54 @@ function createImplement( base, ifaces, cname )
 
 function createUse( base, traits )
 {
+    // invoking the partially applied class will immediately complete its
+    // definition and instantiate it with the provided constructor arguments
     var partial = function()
     {
-        return partial.extend( {} ).apply( null, arguments );
+        return createMixedClass( base, traits )
+            .apply( null, arguments );
     };
 
+    // otherwise, its definition is deferred until additional context is
+    // given during the extend operation
     partial.extend = function()
     {
         var args     = Array.prototype.slice.call( arguments ),
             dfn      = args.pop(),
             ext_base = args.pop();
 
-        // "mix" each trait into the provided definition object
+        // extend the mixed class, which ensures that all super references
-        for ( var i = 0, n = traits.length; i < n; i++ )
+        // are properly resolved
-        {
+        return extend.call( null,
-            traits[ i ].__mixin( dfn );
+            createMixedClass( ( base || ext_base ), traits ),
+            dfn
+        );
+    };
+
+    return partial;
 }
 
-        var C    = extend.call( null, ( base || ext_base ), dfn ),
+
+function createMixedClass( base, traits )
+{
+    // generated definition for our [abstract] class that will mix in each
+    // of the provided traits; it will automatically be marked as abstract
+    // if needed
+    var dfn = { ___$$auto$abstract$$: true };
+
+    // this object is used as a class-specific context for storing trait
+    // data; it will be encapsulated within a ctor closure and will not be
+    // attached to any class
+    var tc = [];
+
+    // "mix" each trait into the class definition object
+    for ( var i = 0, n = traits.length; i < n; i++ )
+    {
+        traits[ i ].__mixin( dfn, tc );
+    }
+
+    // create the mixed class from the above generated definition
+    var C    = extend.call( null, base, dfn ),
         meta = ClassBuilder.getMeta( C );
 
     // add each trait to the list of implemented types so that the
@@ -407,9 +437,6 @@ function createUse( base, traits )
     }
 
     return C;
-    };
-
-    return partial;
 }