Home → Robotlegs 2 →

Guards and Hooks

• Edit

Seth Gilmer

20 Jan, 2013 05:04 AM

Guards and Hooks… what are they? For what reason we should use them? Is there any articles/examples to see them in action? I've tried to find it, but didn't understand at all.

1. Support Staff 1 Posted by Ondina D.F. on 21 Jan, 2013 04:10 PM

   

   Hi Seth,

   You’re right, there are no examples (yet) showing how to use guards and hooks.

   For now, you could take a look at the readme files and the tests on github to get a general idea about guards and hooks:

   https://github.com/robotlegs/robotlegs-framework/tree/master/src/ro...

   https://github.com/robotlegs/robotlegs-framework/tree/master/src/ro...

   Guards
   https://github.com/robotlegs/robotlegs-framework/blob/master/test/r...

   https://github.com/robotlegs/robotlegs-framework/blob/master/test/r...

   Hooks
   https://github.com/robotlegs/robotlegs-framework/blob/master/test/r...

   https://github.com/robotlegs/robotlegs-framework/blob/master/test/r...

   I haven’t used guards and hooks until now. A really silly example here:

   In context config:

   const expectedViewWidth:Number = 100;
   const expectedViewHeight:Number = 200;
               
   injector.map(Number, 'rectHeight').toValue(expectedViewHeight);
   injector.map(Number, 'rectWidth').toValue(expectedViewWidth);
                                   
   _viewProcessorMap.map(HookedView).toNoProcess().withHooks(HookedMediator).withGuards(HookedMediator);
   

   public class HookedMediator extends Mediator
   {       
       [Inject]
       public var view:HookedView;
           
       [Inject(name="rectWidth")]
       public var rectWidth:Number;
           
       [Inject(name="rectHeight")]
       public var rectHeight:Number;
                   
       override public function initialize():void
       {
           trace("HookedMediator.initialize()");//[3]        
       }
       public function hook():void
       {//HOOK 
           trace("HookedMediator.hook()");//[2]      
           view.graphics.beginFill(0x00CC00);
           view.graphics.drawRect(0, 0, rectWidth, rectHeight);
       }
       public function approve():Boolean
       {//GUARD
           trace("HookedMediator.approve()");//[1]       
           return (view.name =="Bender");
       }
   }
   

   In plain text: if View’s name is Bender, draw a rectangle before running Mediator’s initialize().
   The guard checks if a certain condition has been met (view.name =="Bender")
   I created a guard inside the Mediator, but any class with an approve() method can be used to check against different conditions.

   _viewProcessorMap.map(HookedView).toNoProcess().withHooks(HookedMediator).withGuards(IsViewVisible);

   IsViewVisible could have an aprove() method like this:

   public function approve():Boolean
   { return (view.visible); }

   HTH
   Ondina

   P.S. Adding Shaun as a guard to approve my example or to talk about more complex scenarios ;-)
   discussionProcessorMap.map(MySillyExample).toNoProcess().withGuards(ShaunSmith);

   • Edit

2. 2 Posted by Seth Gilmer on 22 Jan, 2013 07:41 AM

   

   Thank you, Ondina.
   It was really helpful. Now I see basic idea.

   • Edit

3. Support Staff 3 Posted by Ondina D.F. on 22 Jan, 2013 10:00 AM

   

   Seth, you’re welcome!!
   I’m closing this discussion for now, but please don’t hesitate to ask more questions in another thread or to re-open this, if need be.

   Ondina

   • Edit

4. Ondina D.F. closed this discussion on 22 Jan, 2013 10:00 AM.