Proxy methods may now override abstract methods

The method for doing so is a kluge; see the test case for more info.

lib/MethodWrappers.js

@@ -89,7 +89,7 @@ exports.standard = {
         // not to keep an unnecessary reference to the keywords object
         var is_static = keywords && keywords[ 'static' ];
 
-        return function()
+        var ret = function()
         {
             var context = getInst( this, cid ) || this,
                 retval  = undefined,
@@ -122,6 +122,13 @@ exports.standard = {
                 ? this
                 : retval;
         };
+
+        // ensures that proxies can be used to provide concrete
+        // implementations of abstract methods with param requirements (we
+        // have no idea what we'll be proxying to at runtime, so we need to
+        // just power through it; see test case for more info)
+        ret.__length = Infinity;
+        return ret;
     },
 };
 

lib/Trait.js

@@ -19,7 +19,8 @@
  *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-var AbstractClass = require( __dirname + '/class_abstract' );
+var AbstractClass = require( __dirname + '/class_abstract' ),
+    ClassBuilder  = require( __dirname + '/ClassBuilder' );
 
 
 function Trait()
@@ -86,12 +87,39 @@ Trait.isTrait = function( trait )
  */
 function createConcrete( acls )
 {
-    // start by providing a concrete implementation for our dummy method
+    // start by providing a concrete implementation for our dummy method and
+    // a constructor that accepts the protected member object of the
+    // containing class
     var dfn = {
         'protected ___$$trait$$': function() {},
+
+        // protected member object
+        'private ___$$pmo$$': null,
+        __construct: function( pmo )
+        {
+            this.___$$pmo$$ = pmo;
+        },
+
+        // mainly for debugging; should really never see this.
+        __name: '#ConcreteTrait#',
     };
 
-    // TODO: everything else
+    // every abstract method should be overridden with a proxy to the
+    // protected member object that will be passed in via the ctor
+    var amethods = ClassBuilder.getMeta( acls ).abstractMethods;
+    for ( var f in amethods )
+    {
+        // TODO: would be nice if this check could be for '___'; need to
+        // replace amethods.__length with something else, then
+        if ( !( Object.hasOwnProperty.call( amethods, f ) )
+            || ( f.substr( 0, 2 ) === '__' )
+        )
+        {
+            continue;
+        }
+
+        dfn[ 'public proxy ' + f ] = '___$$pmo$$';
+    }
 
     return acls.extend( dfn );
 }
@@ -135,7 +163,6 @@ function mixin( trait, dfn )
  */
 function mixMethods( src, dest, vis, iname )
 {
-    // TODO: ignore abstract
     for ( var f in src )
     {
         if ( !( Object.hasOwnProperty.call( src, f ) ) )
@@ -151,19 +178,31 @@ function mixMethods( src, dest, vis, iname )
             continue;
         }
 
+        // if abstract, then we are expected to provide the implementation;
+        // otherwise, we proxy to the trait's implementation
+        if ( src[ f ].___$$keywords$$['abstract'] )
+        {
+            // copy the abstract definition (N.B. this does not copy the
+            // param names, since that is not [yet] important)
+            dest[ 'weak abstract ' + f ] = src[ f ].definition;
+        }
+        else
+        {
             var pname = vis + ' proxy ' + f;
 
-        // if we have already set up a proxy for a field of this name, then
+            // if we have already set up a proxy for a field of this name,
-        // multiple traits have defined the same concrete member
+            // then multiple traits have defined the same concrete member
             if ( dest[ pname ] !== undefined )
             {
                 // TODO: between what traits?
                 throw Error( "Trait member conflict: `" + f + "'" );
             }
 
-        // proxy this method to what will be the encapsulated trait object
+            // proxy this method to what will be the encapsulated trait
+            // object
             dest[ pname ] = iname;
         }
+    }
 }
 
 

test/MemberBuilderValidator/MethodTest.js

@@ -296,7 +296,6 @@ require( 'common' ).testCase(
             name  = 'foo',
             amethod = _self.util.createAbstractMethod( [ 'one' ] );
 
-
         // abstract appears before
         this.quickFailureTest( name, 'compatible', function()
         {

test/MethodWrappersTest.js

@@ -389,5 +389,27 @@ require( 'common' ).testCase(
             "Should properly proxy to static membesr via static accessor method"
         );
     },
+
+
+    /**
+     * A proxy method should be able to be used as a concrete implementation
+     * for an abstract method; this means that it must properly expose the
+     * number of arguments of the method that it is proxying to. The problem
+     * is---it can't, because we do not have a type system and so we cannot
+     * know what we will be proxying to at runtime!
+     *
+     * As such, we have no choice (since validations are not at proxy time)
+     * but to set the length to something ridiculous so that it will never
+     * fail.
+     */
+    'Proxy methods are able to satisfy abstract method param requirements':
+    function()
+    {
+        var f = this._sut.standard.wrapProxy(
+            {}, null, 0, function() {}, '', {}
+        );
+
+        this.assertEqual( f.__length, Infinity );
+    },
 } );
 

test/Trait/AbstractTest.js

@@ -0,0 +1,103 @@
+/**
+ * Tests basic trait definition
+ *
+ *  Copyright (C) 2014 Mike Gerwitz
+ *
+ *  This file is part of GNU ease.js.
+ *
+ *  ease.js is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+require( 'common' ).testCase(
+{
+    caseSetUp: function()
+    {
+        this.Sut           = this.require( 'Trait' );
+        this.Class         = this.require( 'class' );
+        this.AbstractClass = this.require( 'class_abstract' );
+    },
+
+
+    /**
+     * If a trait contains an abstract member, then any class that uses it
+     * should too be considered abstract if no concrete implementation is
+     * provided.
+     */
+    'Abstract traits create abstract classes when used': function()
+    {
+        var T = this.Sut( { 'abstract foo': [] } );
+
+        var _self = this;
+        this.assertDoesNotThrow( function()
+        {
+            // no concrete `foo; should be abstract (this test is sufficient
+            // because AbstractClass will throw an error if there are no
+            // abstract members)
+            _self.AbstractClass.use( T ).extend( {} );
+        }, Error );
+    },
+
+
+    /**
+     * A class may still be concrete even if it uses abstract traits so long
+     * as it provides concrete implementations for each of the trait's
+     * abstract members.
+     */
+    'Concrete classes may use abstract traits by definining members':
+    function()
+    {
+        var T      = this.Sut( { 'abstract traitfoo': [ 'foo' ] } ),
+            C      = null,
+            called = false;
+
+        var _self = this;
+        this.assertDoesNotThrow( function()
+        {
+            C = _self.Class.use( T ).extend(
+            {
+                traitfoo: function( foo ) { called = true; },
+            } );
+        } );
+
+        // sanity check
+        C().traitfoo();
+        this.assertOk( called );
+    },
+
+
+    /**
+     * The concrete methods provided by a class must be compatible with the
+     * abstract definitions of any used traits. This test ensures not only
+     * that the check is being performed, but that the abstract declaration
+     * is properly inherited from the trait.
+     *
+     * TODO: The error mentions "supertype" compatibility, which (although
+     * true) may be confusing; perhaps reference the trait that declared the
+     * method as abstract.
+     */
+    'Concrete classes must be compatible with abstract traits': function()
+    {
+        var T      = this.Sut( { 'abstract traitfoo': [ 'foo' ] } );
+
+        var _self = this;
+        this.assertThrows( function()
+        {
+            C = _self.Class.use( T ).extend(
+            {
+                // missing param in definition
+                traitfoo: function() { called = true; },
+            } );
+        } );
+    },
+} );