introduced Function#bind for the Ruby side;

setting this to nil does not end up as undefined - there seems no way to pass undefined as a function context thus pass the global object (mirroring non-strict mode)

lib/rhino/rhino_ext.rb

@@ -152,11 +152,22 @@ class Java::OrgMozillaJavascript::BaseFunction
   # make JavaScript functions callable Ruby style e.g. `fn.call('42')`
   def call(*args)
     context = Rhino::JS::Context.enter; scope = current_scope(context)
-    __call__(context, scope, nil, Rhino.args_to_javascript(args, scope))
+    # calling as a (var) stored function - no this === undefined "use strict"
+    # TODO can't pass Undefined.instance as this - it's not a Scriptable !?
+    this = Rhino::JS::ScriptRuntime.getGlobal(context)
+    __call__(context, scope, this, Rhino.args_to_javascript(args, scope))
   ensure
     Rhino::JS::Context.exit
   end
   
+  def bind(this, *args)
+    context = Rhino::JS::Context.enter; scope = current_scope(context)
+    args = Rhino.args_to_javascript(args, scope)
+    Rhino::JS::BoundFunction.new(context, scope, self, Rhino.to_javascript(this), args)
+  ensure
+    Rhino::JS::Context.exit    
+  end
+  
   # use JavaScript functions constructors from Ruby as `fn.new`
   def new(*args)
     context = Rhino::JS::Context.enter; scope = current_scope(context)
@@ -167,7 +178,8 @@ class Java::OrgMozillaJavascript::BaseFunction
   
   def methodcall(this, *args)
     context = Rhino::JS::Context.enter; scope = current_scope(context)
-    __call__(context, scope, Rhino.to_javascript(this), Rhino.args_to_javascript(args, scope))
+    args = Rhino.args_to_javascript(args, scope)
+    __call__(context, scope, Rhino.to_javascript(this), args)
   ensure
     Rhino::JS::Context.exit
   end

spec/rhino/rhino_ext_spec.rb

@@ -118,14 +118,14 @@ describe "NativeFunction" do
       
   before do
     factory = Rhino::JS::ContextFactory.new
-    context, scope = nil, nil
+    @context, @scope = nil, nil
     factory.call do |ctx|
-      context = ctx
-      scope = context.initStandardObjects(nil, false)
+      @context = ctx
+      @scope = @context.initStandardObjects(nil, false)
     end
-    factory.enterContext(context)
+    factory.enterContext(@context)
     
-    object = context.newObject(scope)
+    object = @context.newObject(@scope)
     @object = Rhino::JS::ScriptableObject.getProperty(object, 'toString')
     @object.instance_eval do
       def to_h_properties
@@ -141,7 +141,34 @@ describe "NativeFunction" do
   it_should_behave_like 'ScriptableObject'
   
   it 'is callable' do
-    @object.call.should == '[object Object]'
+    # NOTE: no implicit or bound this thus this === global
+    @object.call.should == '[object global]'
+  end
+  
+  it 'might be bind and called' do
+    @object.bind(@object).should be_a(Rhino::JS::Function)
+    @object.bind(@object).call.should == '[object Function]'
+  end
+  
+  it 'might be bind to a this context' do
+    @object.bind(@object).should be_a(Rhino::JS::Function)
+    @object.bind(@object).call.should == '[object Function]'
+  end
+
+  it 'might be bind to a this with args' do
+    array = @context.newArray(@scope, [].to_java)
+    push = Rhino::JS::ScriptableObject.getProperty(array, 'push')
+    
+    this = @context.newArray(@scope, [ 0 ].to_java)
+    push.bind(this, 1, 2).call(3, 4)
+    
+    this.length.should == 5
+    5.times { |i| this.get(i, this).should == i }
+  end
+  
+  it 'might be method-called' do
+    an_obj = @context.newObject(@scope)
+    @object.methodcall(an_obj).should == '[object Object]'
   end
   
 end