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Adobe Flex: Program in Style or an Elevator Pitch

All students usually get excited by Adobe Flex, but each of them comes with different understanding of how to do things right

From Farata  Systems blog

We usually run Flex training for  private clients of Farata Systems , but once in a while we teach public classes for people with different programming background (my next Flex class at New York University starts in November).  All students usually get excited by Adobe Flex, but each of them comes with different understanding of how to do things right. So I’ll tell you the  story  that might have happened in a real life, but first, let me remind you of an old Indian tale about seven blind men and an elephant .  In short, one blind man touched the elephant’s head, the other one touched the tail, someone was by the leg. And each of them visualized an elephant differently based on what he touched…

My students usually arrive to the classroom early, but this time three seats were empty. Five minutes later I got a phone call from one of them explaining that they got stuck in the elevator and will stay there for another fifteen minute until the serviceman arrives. Needless to say that each of them had a laptop (do not leave home without it), so I gave them a short assignment to trying to help them use this time productively.

Here’s the assignment: Create a Window with a Panel  that can resize itself by clicking on the button +/- that is located in the right corner of the panel. One click should minimize the panel’s  height to  20 pixels, and a  subsequent  one should maximize to 100 pixels, and so on. 

For example, these are the two states of such panel:

 I forgot  to tell you that one of these guys was a Cobol programmer, the other one had Java background, and the third one was a Smalltalk fan.

From  Cobol to Flex

The Cobol programmer thought to himself,”I used to write long programs because during job interviews they would  ask how many lines of code did I write. These guys are different, so to earn a good grade, this program should be small ”. He finished the program on time and this is what it looked like:

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" layout="absolute">
     <mx:Panel id="thePanel" title="The Panel" height="90" width="100%" headerHeight="20" />
     <mx:HBox width="100%" horizontalAlign="right" paddingRight="2">
       <mx:Label text="-"  fontSize="16" width="20" height="17" fontWeight="bold"
             id="minimizeActions"
             click="{if (minimizeActions.text=='+'){
                          minimizeActions.text='-';
                          thePanel.height=100;
                      } else {
                         minimizeActions.text='+';
                          thePanel.height=20;
                      }
                     }" />
     </mx:HBox>  
</mx:Application>

From  Java  to Flex

The Java programmer thought, “The standard Flex Panel class does not have the  property that remembers the current state of the Panel, but Flex components are easily extendable, so I’ll create a descendent of the Panel in ActionScript, add a private  state flag (minimized) , public setter and getter,  and resize function. This way my new Panel class will be reusable and self contained.”  This is his reusable ActionScript class called ResizableJPanel:

package {
            import mx.containers.Panel;
            public class ResizableJPanel extends Panel   {
                        // state of the panel
                       private  var isPanelMinimized:Boolean;                       

                        public function get minimized():Boolean{
                            return isPanelMinimized;    
                        }

                       public function set minimized(state:Boolean){
                             isPanelMinimized=state;
                        }
                        
                       public function resizeMe():void{
   
                        if (minimized){
        
                       minimized=false;
         
                     height=maxHeight;
           
                } else {
               
                 minimized=true;
                 
              height=minHeight;
                    
       }
            }    
  }       
}

This is Javist's  mxml code:

<?xml version="1.0" encoding="utf-8"?>

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" xmlns:local="*" layout="absolute"
     applicationComplete="minimizeActions.addEventListener(MouseEvent.CLICK, resizePanel);">
   <mx:Canvas id="theCanvas" height="100" width="100%" >                
     <local:ResizableJPanel id="thePanel"  height="90" width="100%"
             title="The Paaanel" minHeight="20" maxHeight="100" headerHeight="20" />
     <mx:HBox width="100%" horizontalAlign="right" paddingRight="2">
       <mx:Label text="-"  fontSize="16" width="20" height="17" fontWeight="bold"
             id="minimizeActions"  />
     </mx:HBox>
   </mx:Canvas>        
  <mx:Script>
       <![CDATA[
        function resizePanel(event:MouseEvent):void{
         if (thePanel.minimized){
             minimizeActions.text="-";
             thePanel.resizeMe();
             theCanvas.height=thePanel.maxHeight;
         } else {
             minimizeActions.text="+";
             thePanel.resizeMe();
             theCanvas.height=thePanel.minHeight;
         }
    }

       ]]>
   </mx:Script>
</mx:Application>

From  Smalltalk to Flex

The Smalltalk guy thought, “Let me see if the standard Panel is a dynamic class. If not I’ll extend  it just to make it dynamic and will be assigning the panel’s state on the fly. I hope Yakov is not one of these object-oriented Nazis”. This is his panel ActionScript class that just adds a dynamic behavior to the Panel:

package{
    import mx.containers.Panel;
    public dynamic class ResizableSmtPanel extends Panel
            {
    }     
}

His mxml class looked like this:

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" xmlns="*" layout="absolute">
     <ResizableSmtPanel title="The Panel" id="thePanel"  height="90" width="100%" 
                            minHeight="20" maxHeight="100" headerHeight="20">
     </ResizableSmtPanel>
     <mx:HBox width="100%" horizontalAlign="right" paddingRight="2">
           <mx:Label text="-"  fontSize="16" width="20" height="17" fontWeight="bold"
             id="minimizeActions" click="resizePanel()" />
      </mx:HBox>
  <mx:Script>

            <![CDATA[

        function resizePanel():void{
             if (thePanel.minimized){
                  minimizeActions.text="-";
                  thePanel.minimized=false;
                 thePanel.height=thePanel.maxHeight;
         } else {
                   minimizeActions.text="+";
                   thePanel.minimized=true;
                   thePanel.height=thePanel.minHeight;
         }
      }
            ]]>
</mx:Script>

Since we are not in the classroom, I’m not going to go to  a code review and lengthy discussions, I will just say the I gave an “A” to each of these guys...and here's the Flex version:

<?xml version="1.0" encoding="utf-8"?>

<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" xmlns="*" layout="absolute">
<mx:Component className="ResizablePanel">
   <mx:Panel>
    <mx:Script>
 
     [Bindable]  
     public var minimized:Boolean = false;
    </mx:Script>
 </mx:Panel>
</mx:Component>

<ResizablePanel title="The Panel" id="thePanel"  minimized="false" height="{thePanel.minimized?thePanel.minHeight:thePanel.maxHeight}" width="99%"
                            minHeight="20" maxHeight="100" headerHeight="20"/>
     <mx:HBox width="99%" horizontalAlign="right" paddingRight="2">
           <mx:Label text="{thePanel.minimized?'+':'-'}"  fontSize="16" width="20" height="17" fontWeight="bold"
             id="minimizeActions" click="{thePanel.minimized=!thePanel.minimized}" />
      </mx:HBox>
</mx:Application>

What’s the morale of this story? Learn another language,  no matter what’s your current background. Initially you will try to bring your own culture to this new language, but eventually your horizons will broaden, which will make you a better programmer.

P.S. Isn’t it  funny that  the Cobol guy’s version was the shortest one? But was it the best one?  Can you offer a different solution?

More Stories By Yakov Fain

Yakov Fain is a Java Champion and a co-founder of the IT consultancy Farata Systems and the product company SuranceBay. He wrote a thousand blogs (http://yakovfain.com) and several books about software development. Yakov authored and co-authored such books as "Angular 2 Development with TypeScript", "Java 24-Hour Trainer", and "Enterprise Web Development". His Twitter tag is @yfain

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Most Recent Comments
Daniel Szmulewicz 06/19/08 12:08:17 PM EDT

Shalom,

OK, so this post is two years old, but I just found it today and appreciated it a lot. Very instructive, indeed. Since you asked for more versions to achieve the desired resizeable canvas, may I offer mine. It is in the line of the Flex version offered at the end, only simplified.

Here it is:
<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml" xmlns="*" layout="absolute">
<mx:Script>
[Bindable]
public var minimized:Boolean = false;
</mx:Script>

<mx:Panel title="The Panel" id="thePanel" height="{minimized?thePanel.minHeight:thePanel.maxHeight}" width="99%" minHeight="20" maxHeight="100" headerHeight="20"/>

<mx:HBox width="99%" horizontalAlign="right" paddingRight="2">
<mx:Label text="{minimized?'+':'-'}" fontSize="16" width="20" height="17" fontWeight="bold" click="{minimized=!minimized}" />
</mx:HBox>
</mx:Application>

Thanks again.

Daniel Szmulewicz

PS: I'm looking for a job. Do I win one?

AJAXWorld News Desk 09/23/06 03:16:38 PM EDT

We usually run Flex training for private clients of Farata Systems, but once in a while we teach public classes for people with different programming background (my next Flex class at New York University starts in November). All students usually get excited by Adobe Flex, but each of them comes with different understanding of how to do things right. So I'll tell you the story that might have happened in a real life, but first, let me remind you of an old Indian tale about seven blind men and an elephant. In short, one blind man touched the elephant's head, the other one touched the tail, someone was by the leg. And each of them visualized an elephant differently based on what he touched.