[flexcoders] Re: How to stop null on delayed execution.

2009-03-10 Thread valdhor 
The problem is that you are instantiating your SimpleExample object and
then trying to modify a component of the object before it is created.

You would need to move the instantiation of TextInput to the constructor
or instantiate it when you create the variable...

package
{
 import mx.containers.VBox;
 import mx.controls.TextInput;
 import mx.events.FlexEvent;

 public class SimpleExample extends VBox
 {
 private var child:TextInput = new TextInput();
 private var _text:String;

 public function SimpleExample()
 {
 super();
 addEventListener(FlexEvent.INITIALIZE, init)
 }

 private function init(event:FlexEvent):void
 {
 addChild(child);
 }

 public function get text():String {
 return _text;
 }

 public function set text(text:String):void {
 this.child.text = text;
 }
 }
}


--- In flexcoders@yahoogroups.com, Wesley Acheson wesley.ache...@...
wrote:

 Hi take for for example the following simple example. Its not a real
world
 example but it does show the problem that I wish to avoid.

 ---
 MXML (simpletest.mxml)
 ---
 ?xml version=1.0 encoding=utf-8?
 mx:Application xmlns:mx=http://www.adobe.com/2006/mxml;
layout=absolute
 xmlns:local=*
 local:SimpleExample text=hello

 /local:SimpleExample
 /mx:Application

 --
 ActionScript SimpleExample.as
 --
 package
 {
 import mx.containers.VBox;
 import mx.controls.TextInput;
 import mx.events.FlexEvent;

 public class SimpleExample extends VBox
 {

 private var child:TextInput;

 private var _text:String;

 public function SimpleExample()
 {
 addEventListener(FlexEvent.INITIALIZE, init)
 }

 private function init(event:FlexEvent):void
 {
 child = new TextInput();
 addChild(child);
 }

 public function get text():String {
 return _text;
 }

 public function set text(text:String):void {
 this.child.text = text;
 }

 }
 }
 
 If this is run I get a null error at set text.  How do I avoid this? 
Should
 I just just listen to the property change event on set text? Imagine
now
 that I had multiple different children.  Is there a method I can
override
 such as commitProperties so that all this will be done in the same
place.

 I'm sorry if this isn't too clear what I asking.

 Wesley Acheson.

[flexcoders] Re: How to stop null on delayed execution.

2009-03-10 Thread Tim Hoff 

Override createChildren() and add the child there; instead of trying to
re-invent the component lifecycle by using INITIALIZE .  And yes,
commitProperties() would be a good place to set the child's text; from
the text property.

-TH

--- In flexcoders@yahoogroups.com, Wesley Acheson wesley.ache...@...
wrote:

 Hi take for for example the following simple example. Its not a real
world
 example but it does show the problem that I wish to avoid.

 ---
 MXML (simpletest.mxml)
 ---
 ?xml version=1.0 encoding=utf-8?
 mx:Application xmlns:mx=http://www.adobe.com/2006/mxml;
layout=absolute
 xmlns:local=*
 local:SimpleExample text=hello

 /local:SimpleExample
 /mx:Application

 --
 ActionScript SimpleExample.as
 --
 package
 {
 import mx.containers.VBox;
 import mx.controls.TextInput;
 import mx.events.FlexEvent;

 public class SimpleExample extends VBox
 {

 private var child:TextInput;

 private var _text:String;

 public function SimpleExample()
 {
 addEventListener(FlexEvent.INITIALIZE, init)
 }

 private function init(event:FlexEvent):void
 {
 child = new TextInput();
 addChild(child);
 }

 public function get text():String {
 return _text;
 }

 public function set text(text:String):void {
 this.child.text = text;
 }

 }
 }
 
 If this is run I get a null error at set text. How do I avoid this?
Should
 I just just listen to the property change event on set text? Imagine
now
 that I had multiple different children. Is there a method I can
override
 such as commitProperties so that all this will be done in the same
place.

 I'm sorry if this isn't too clear what I asking.

 Wesley Acheson.

Re: [flexcoders] Re: How to stop null on delayed execution.

2009-03-10 Thread Wesley Acheson 
Thanks I thought that always initialising either in the constructor or in
the variable declaration was a bit hacky.  It is what I've been doing up
till now. Is there any refrence for a component (particualy containers) life
cycle?

Off topic in gmail I autoarchive flex coders emails.  Does anyone know of a
way to not auto archive treads that I've been involved with?

Regards,

Wesley Acheson

On Tue, Mar 10, 2009 at 5:40 PM, Tim Hoff timh...@aol.com wrote:


 Override createChildren() and add the child there; instead of trying to
 re-invent the component lifecycle by using INITIALIZE .  And yes,
 commitProperties() would be a good place to set the child's text; from
 the text property.

 -TH

 --- In flexcoders@yahoogroups.com, Wesley Acheson wesley.ache...@...
 wrote:
 
  Hi take for for example the following simple example. Its not a real
 world
  example but it does show the problem that I wish to avoid.
 
  ---
  MXML (simpletest.mxml)
  ---
  ?xml version=1.0 encoding=utf-8?
  mx:Application xmlns:mx=http://www.adobe.com/2006/mxml;
 layout=absolute
  xmlns:local=*
  local:SimpleExample text=hello
 
  /local:SimpleExample
  /mx:Application
 
  --
  ActionScript SimpleExample.as
  --
  package
  {
  import mx.containers.VBox;
  import mx.controls.TextInput;
  import mx.events.FlexEvent;
 
  public class SimpleExample extends VBox
  {
 
  private var child:TextInput;
 
  private var _text:String;
 
  public function SimpleExample()
  {
  addEventListener(FlexEvent.INITIALIZE, init)
  }
 
  private function init(event:FlexEvent):void
  {
  child = new TextInput();
  addChild(child);
  }
 
  public function get text():String {
  return _text;
  }
 
  public function set text(text:String):void {
  this.child.text = text;
  }
 
  }
  }
  
  If this is run I get a null error at set text. How do I avoid this?
 Should
  I just just listen to the property change event on set text? Imagine
 now
  that I had multiple different children. Is there a method I can
 override
  such as commitProperties so that all this will be done in the same
 place.
 
  I'm sorry if this isn't too clear what I asking.
 
  Wesley Acheson.
 





 

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[flexcoders] Re: How to stop null on delayed execution.

2009-03-10 Thread Tim Hoff 

Hi Wesley,

Controls and Containers all extend UIComponent.  For your case, take a
look at the code for UIComponent and VBox (F3, with the mouse over a
classs name, in FB or Eclipse).  Or, just look at any custom component
out there; for an example.

-TH

--- In flexcoders@yahoogroups.com, Wesley Acheson wesley.ache...@...
wrote:

 Thanks I thought that always initialising either in the constructor or
in
 the variable declaration was a bit hacky. It is what I've been doing
up
 till now. Is there any refrence for a component (particualy
containers) life
 cycle?

 Off topic in gmail I autoarchive flex coders emails. Does anyone know
of a
 way to not auto archive treads that I've been involved with?

 Regards,

 Wesley Acheson

 On Tue, Mar 10, 2009 at 5:40 PM, Tim Hoff timh...@... wrote:

 
  Override createChildren() and add the child there; instead of trying
to
  re-invent the component lifecycle by using INITIALIZE . And yes,
  commitProperties() would be a good place to set the child's text;
from
  the text property.
 
  -TH
 
  --- In flexcoders@yahoogroups.com, Wesley Acheson wesley.acheson@
  wrote:
  
   Hi take for for example the following simple example. Its not a
real
  world
   example but it does show the problem that I wish to avoid.
  
   ---
   MXML (simpletest.mxml)
   ---
   ?xml version=1.0 encoding=utf-8?
   mx:Application xmlns:mx=http://www.adobe.com/2006/mxml;
  layout=absolute
   xmlns:local=*
   local:SimpleExample text=hello
  
   /local:SimpleExample
   /mx:Application
  
   --
   ActionScript SimpleExample.as
   --
   package
   {
   import mx.containers.VBox;
   import mx.controls.TextInput;
   import mx.events.FlexEvent;
  
   public class SimpleExample extends VBox
   {
  
   private var child:TextInput;
  
   private var _text:String;
  
   public function SimpleExample()
   {
   addEventListener(FlexEvent.INITIALIZE, init)
   }
  
   private function init(event:FlexEvent):void
   {
   child = new TextInput();
   addChild(child);
   }
  
   public function get text():String {
   return _text;
   }
  
   public function set text(text:String):void {
   this.child.text = text;
   }
  
   }
   }
   
   If this is run I get a null error at set text. How do I avoid
this?
  Should
   I just just listen to the property change event on set text?
Imagine
  now
   that I had multiple different children. Is there a method I can
  override
   such as commitProperties so that all this will be done in the same
  place.
  
   I'm sorry if this isn't too clear what I asking.
  
   Wesley Acheson.
  
 
 
 
 
 
  
 
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[flexcoders] Re: How to stop null on delayed execution.

2009-03-10 Thread sunild999999 
--- In flexcoders@yahoogroups.com, Wesley Acheson wesley.ache...@... wrote:

  Is there any refrence for a component (particualy containers) life
 cycle?
 


This page in the Flex Developer's Guide was very helpful in explaining how to 
override the Flex component life cycle methods.  I also recommend reading the 
pages before/after this page as well:

http://livedocs.adobe.com/flex/3/html/ascomponents_advanced_3.html#209794

[flexcoders] Re: How to stop null on delayed execution.

2009-03-10 Thread valdhor 
Why?

Standard OOP practice is to initialize variables in the constructor (That's 
what it's there for).


--- In flexcoders@yahoogroups.com, Wesley Acheson wesley.ache...@... wrote:

 Thanks I thought that always initialising either in the constructor
 or in the variable declaration was a bit hacky.

Re: [flexcoders] Re: How to stop null on delayed execution.

2009-03-10 Thread Wesley Acheson 
On Tue, Mar 10, 2009 at 6:42 PM, Tim Hoff timh...@aol.com wrote:


 Hi Wesley,

 Controls and Containers all extend UIComponent.  For your case, take a
 look at the code for UIComponent and VBox (F3, with the mouse over a
 classs name, in FB or Eclipse).  Or, just look at any custom component
 out there; for an example.

 -TH

 --- In flexcoders@yahoogroups.com, Wesley Acheson wesley.ache...@...
 wrote:
 
  Thanks I thought that always initialising either in the constructor or
 in
  the variable declaration was a bit hacky. It is what I've been doing
 up
  till now. Is there any refrence for a component (particualy
 containers) life
  cycle?
 
  Off topic in gmail I autoarchive flex coders emails. Does anyone know
 of a
  way to not auto archive treads that I've been involved with?
 
  Regards,
 
  Wesley Acheson
 


Thanks Tim,

This is helpfull but I find it difficult to inspect classes in the core
libary as.

   1. Instance highlightling doesn't work.
   2. F3 doesn't take you to a declaration.
   3. It doesn't actually tell you when an event is raised or a method is
   called by looking at the methods as their often called outside the class
   itself.


I'll however make more of an effort to look.

Wes

Re: [flexcoders] Re: How to stop null on delayed execution.

2009-03-10 Thread Wesley Acheson 
On Tue, Mar 10, 2009 at 7:44 PM, sunild99 sunilbd...@gmail.com wrote:


 This page in the Flex Developer's Guide was very helpful in explaining how
 to override the Flex component life cycle methods.  I also recommend reading
 the pages before/after this page as well:

 http://livedocs.adobe.com/flex/3/html/ascomponents_advanced_3.html#209794


Thanks I'll take a look.

Wes

Re: [flexcoders] Re: How to stop null on delayed execution.

2009-03-10 Thread Wesley Acheson 
Because of a visual components life cycle mainly. If I was to write an
application in actionscript (asside from the root mxml file - I don't think
you can do that in AS) all visual components would be initialised
immediatly.

Lazy loading is also used quite commonly as an OOP pattern.

Also constructor initialisation falls out of grace, (I think) with stuff
like spring in java as it doesn't allow well for dependency injection.

Finally Its just nice for people using your custom components if they act
like other components.  It means less to learn.

These are just opinions though I have mostly been writing my code in the
same way as you gave in the example. i.e.

private var someVar:someClass = new someClass();

Thanks for your help too though.  I did change my real class *not* the
simplified example to do that when I got your reply as I needed to get it
working quickly.

On Tue, Mar 10, 2009 at 8:05 PM, valdhor valdhorli...@embarqmail.comwrote:

 Why?

 Standard OOP practice is to initialize variables in the constructor (That's
 what it's there for).


 --- In flexcoders@yahoogroups.com, Wesley Acheson wesley.ache...@...
 wrote:
 
  Thanks I thought that always initialising either in the constructor
  or in the variable declaration was a bit hacky.



 

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 Alternative FAQ location:
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