stopped using __proto__, instead, using a variant of goog.inherits for extends and super()

Author: jashkenas

documentation/cs/super.cs

@@ -3,13 +3,13 @@
   alert(this.name + " moved " + meters + "m.").
 
 Snake: name => this.name: name.
-Snake extends new Animal()
+Snake extends Animal
 Snake.prototype.move: =>
   alert("Slithering...")
   super(5).
 
 Horse: name => this.name: name.
-Horse extends new Animal()
+Horse extends Animal
 Horse.prototype.move: =>
   alert("Galloping...")
   super(45).

documentation/js/super.js

@@ -8,19 +8,23 @@
     this.name = name;
     return this.name;
   };
-  Snake.prototype.__proto__ = new Animal();
+  Snake.__superClass__ = Animal.prototype;
+  Snake.prototype = new Animal();
+  Snake.prototype.constructor = Snake;
   Snake.prototype.move = function() {
     alert("Slithering...");
-    return Snake.prototype.__proto__.move.call(this, 5);
+    return Snake.__superClass__.move.call(this, 5);
   };
   var Horse = function(name) {
     this.name = name;
     return this.name;
   };
-  Horse.prototype.__proto__ = new Animal();
+  Horse.__superClass__ = Animal.prototype;
+  Horse.prototype = new Animal();
+  Horse.prototype.constructor = Horse;
   Horse.prototype.move = function() {
     alert("Galloping...");
-    return Horse.prototype.__proto__.move.call(this, 45);
+    return Horse.__superClass__.move.call(this, 45);
   };
   var sam = new Snake("Sammy the Python");
   var tom = new Horse("Tommy the Palomino");

examples/code.cs

@@ -145,13 +145,13 @@ aliquam erat volutpat. Ut wisi enim ad."
   alert(this.name + " moved " + meters + "m.").
 
 Snake: name => this.name: name.
-Snake extends new Animal()
+Snake extends Animal
 Snake.prototype.move: =>
   alert('Slithering...')
   super(5).
 
 Horse: name => this.name: name.
-Horse extends new Animal()
+Horse extends Animal
 Horse.prototype.move: =>
   alert('Galloping...')
   super(45).

index.html

@@ -610,13 +610,13 @@ <h2>Language Reference</h2>
   alert(<span class="Variable">this</span>.name <span class="Keyword">+</span> <span class="String"><span class="String">&quot;</span> moved <span class="String">&quot;</span></span> <span class="Keyword">+</span> meters <span class="Keyword">+</span> <span class="String"><span class="String">&quot;</span>m.<span class="String">&quot;</span></span>).
 
 <span class="FunctionName">Snake</span><span class="Keyword">:</span> <span class="FunctionArgument">name</span> <span class="Storage">=&gt;</span> <span class="Variable">this</span>.name<span class="Keyword">:</span> name.
-Snake <span class="Variable">extends</span> <span class="Keyword">new</span> <span class="TypeName">Animal</span>()
+Snake <span class="Variable">extends</span> Animal
 <span class="FunctionName">Snake.prototype.move</span><span class="Keyword">:</span> <span class="Storage">=&gt;</span>
   alert(<span class="String"><span class="String">&quot;</span>Slithering...<span class="String">&quot;</span></span>)
   <span class="Variable">super</span>(<span class="Number">5</span>).
 
 <span class="FunctionName">Horse</span><span class="Keyword">:</span> <span class="FunctionArgument">name</span> <span class="Storage">=&gt;</span> <span class="Variable">this</span>.name<span class="Keyword">:</span> name.
-Horse <span class="Variable">extends</span> <span class="Keyword">new</span> <span class="TypeName">Animal</span>()
+Horse <span class="Variable">extends</span> Animal
 <span class="FunctionName">Horse.prototype.move</span><span class="Keyword">:</span> <span class="Storage">=&gt;</span>
   alert(<span class="String"><span class="String">&quot;</span>Galloping...<span class="String">&quot;</span></span>)
   <span class="Variable">super</span>(<span class="Number">45</span>).
@@ -639,19 +639,23 @@ <h2>Language Reference</h2>
   <span class="Variable">this</span>.<span class="LibraryConstant">name</span> <span class="Keyword">=</span> name;
   <span class="Keyword">return</span> <span class="Variable">this</span>.<span class="LibraryConstant">name</span>;
 };
-<span class="LibraryClassType">Snake</span>.<span class="LibraryConstant">prototype</span>.<span class="FunctionName">__proto__</span> = <span class="Keyword">new</span> <span class="TypeName">Animal</span>();
+Snake.__superClass__ <span class="Keyword">=</span> Animal.<span class="LibraryConstant">prototype</span>;
+<span class="LibraryClassType">Snake</span>.<span class="LibraryConstant">prototype</span> = <span class="Keyword">new</span> <span class="TypeName">Animal</span>();
+<span class="LibraryClassType">Snake</span>.<span class="LibraryConstant">prototype</span>.<span class="FunctionName">constructor</span> = Snake;
 <span class="LibraryClassType">Snake</span>.<span class="LibraryConstant">prototype</span>.<span class="FunctionName">move</span> = <span class="Storage">function</span>() {
   <span class="LibraryFunction">alert</span>(<span class="String"><span class="String">&quot;</span>Slithering...<span class="String">&quot;</span></span>);
-  <span class="Keyword">return</span> Snake.<span class="LibraryConstant">prototype</span>.__proto__.move.<span class="LibraryFunction">call</span>(<span class="Variable">this</span>, <span class="Number">5</span>);
+  <span class="Keyword">return</span> Snake.__superClass__.move.<span class="LibraryFunction">call</span>(<span class="Variable">this</span>, <span class="Number">5</span>);
 };
 <span class="Storage">var</span> <span class="FunctionName">Horse</span> = <span class="Storage">function</span>(<span class="FunctionArgument">name</span>) {
   <span class="Variable">this</span>.<span class="LibraryConstant">name</span> <span class="Keyword">=</span> name;
   <span class="Keyword">return</span> <span class="Variable">this</span>.<span class="LibraryConstant">name</span>;
 };
-<span class="LibraryClassType">Horse</span>.<span class="LibraryConstant">prototype</span>.<span class="FunctionName">__proto__</span> = <span class="Keyword">new</span> <span class="TypeName">Animal</span>();
+Horse.__superClass__ <span class="Keyword">=</span> Animal.<span class="LibraryConstant">prototype</span>;
+<span class="LibraryClassType">Horse</span>.<span class="LibraryConstant">prototype</span> = <span class="Keyword">new</span> <span class="TypeName">Animal</span>();
+<span class="LibraryClassType">Horse</span>.<span class="LibraryConstant">prototype</span>.<span class="FunctionName">constructor</span> = Horse;
 <span class="LibraryClassType">Horse</span>.<span class="LibraryConstant">prototype</span>.<span class="FunctionName">move</span> = <span class="Storage">function</span>() {
   <span class="LibraryFunction">alert</span>(<span class="String"><span class="String">&quot;</span>Galloping...<span class="String">&quot;</span></span>);
-  <span class="Keyword">return</span> Horse.<span class="LibraryConstant">prototype</span>.__proto__.move.<span class="LibraryFunction">call</span>(<span class="Variable">this</span>, <span class="Number">45</span>);
+  <span class="Keyword">return</span> Horse.__superClass__.move.<span class="LibraryFunction">call</span>(<span class="Variable">this</span>, <span class="Number">45</span>);
 };
 <span class="Storage">var</span> sam <span class="Keyword">=</span> <span class="Keyword">new</span> <span class="TypeName">Snake</span>(<span class="String"><span class="String">&quot;</span>Sammy the Python<span class="String">&quot;</span></span>);
 <span class="Storage">var</span> tom <span class="Keyword">=</span> <span class="Keyword">new</span> <span class="TypeName">Horse</span>(<span class="String"><span class="String">&quot;</span>Tommy the Palomino<span class="String">&quot;</span></span>);
@@ -666,19 +670,23 @@ <h2>Language Reference</h2>
   this.name = name;
   return this.name;
 };
-Snake.prototype.__proto__ = new Animal();
+Snake.__superClass__ = Animal.prototype;
+Snake.prototype = new Animal();
+Snake.prototype.constructor = Snake;
 Snake.prototype.move = function() {
   alert("Slithering...");
-  return Snake.prototype.__proto__.move.call(this, 5);
+  return Snake.__superClass__.move.call(this, 5);
 };
 var Horse = function(name) {
   this.name = name;
   return this.name;
 };
-Horse.prototype.__proto__ = new Animal();
+Horse.__superClass__ = Animal.prototype;
+Horse.prototype = new Animal();
+Horse.prototype.constructor = Horse;
 Horse.prototype.move = function() {
   alert("Galloping...");
-  return Horse.prototype.__proto__.move.call(this, 45);
+  return Horse.__superClass__.move.call(this, 45);
 };
 var sam = new Snake("Sammy the Python");
 var tom = new Horse("Tommy the Palomino");

lib/coffee_script/grammar.y

@@ -259,7 +259,7 @@ rule
 
   # Extending an object's prototype.
   Extends:
-    Value EXTENDS Expression          { result = ExtendsNode.new(val[0], val[2]) }
+    Value EXTENDS Value               { result = ExtendsNode.new(val[0], val[2]) }
   ;
 
   # A generic function invocation.
@@ -316,6 +316,7 @@ rule
   ;
 
   # Array comprehensions, including guard and current index.
+  # Looks a little confusing, check nodes.rb for the arguments to ForNode.
   For:
     Expression FOR
       ForVariables ForSource          { result = ForNode.new(val[0], val[3][0], val[2][0], val[3][1], val[2][1]) }

lib/coffee_script/nodes.rb

@@ -211,11 +211,12 @@ def compile(o={})
     def compile_super(args, o)
       methname = o[:last_assign].sub(LEADING_DOT, '')
       arg_part = args.empty? ? '' : ", #{args}"
-      "#{o[:proto_assign]}.prototype.__proto__.#{methname}.call(this#{arg_part})"
+      "#{o[:proto_assign]}.__superClass__.#{methname}.call(this#{arg_part})"
     end
   end
 
   # Node to extend an object's prototype with an ancestor object.
+  # After goog.inherits from the Closure Library.
   class ExtendsNode < Node
     attr_reader :sub_object, :super_object
 
@@ -224,7 +225,10 @@ def initialize(sub_object, super_object)
     end
 
     def compile(o={})
-      "#{@sub_object.compile(o)}.prototype.__proto__ = #{@super_object.compile(o)}"
+      sub, sup = @sub_object.compile(o), @super_object.compile(o)
+      "#{sub}.__superClass__ = #{sup}.prototype;\n#{o[:indent]}" +
+      "#{sub}.prototype = new #{sup}();\n#{o[:indent]}" +
+      "#{sub}.prototype.constructor = #{sub}"
     end
 
   end

test/fixtures/execution/calling_super.cs

@@ -3,17 +3,17 @@
   'zero/' + string.
 
 FirstChild: => .
-FirstChild extends new Base()
+FirstChild extends Base
 FirstChild.prototype.func: string =>
   super('one/') + string.
 
 SecondChild: => .
-SecondChild extends new FirstChild()
+SecondChild extends FirstChild
 SecondChild.prototype.func: string =>
   super('two/') + string.
 
 ThirdChild: => .
-ThirdChild extends new SecondChild()
+ThirdChild extends SecondChild
 ThirdChild.prototype.func: string =>
   super('three/') + string.