When you create an mxml file you really are creating a subclass. The
mxml is converted to AS before compiling. If you tell the compiler to
keep generated files, you can see exactly what this looks like, and
convince yourself that it's true.
I think what happens with ServiceLocator is this: you create an instance
of your subclass of ServiceLocator (call it MyLocator) as a child of
your application. When the application is instantiated, the Flex
framework creates an instance of MyLocator by invoking its constructor.
Since MyLocator does not define a constructor, the constructor of its
superclass, ServiceLocator, is invoked. If you look at ServiceLocator's
constructor, you'll see that it assigns 'this' to the class member
serviceLocator. The important thing to realize here is that 'this' is an
instance of MyLocator, not ServiceLocator. So, subsequent calls to
ServiceLocator.getInstance() returns an instance of MyLocator.
Some fancy footwork here, to be sure.
Tobias.
-----Original Message-----
From: flexcoders@yahoogroups.com [mailto:[EMAIL PROTECTED] On
Behalf Of Larry Liang
Sent: Thursday, April 27, 2006 5:22 AM
To: flexcoders@yahoogroups.com
Subject: [flexcoders] Re: How to subclass a singleton class ----
cairngorm issue --- Please help!!
Thanks a lot michael.
A step by step example would be extremely helpful. I'm sure it will
help me clarify a few things.
Please email the code to this email address: [EMAIL PROTECTED]
I re-think about the whole issue again and guess the thing that I
would like to figure out here is what exactly happens in flex when
you do this:
<cairngorm:ServiceLocator xmlns:mx="http://www.macromedia.com/2003/
mxml" xmlns:cairngorm="org.nevis.cairngorm.business.*" >
<mx:RemoteObject id="customerDelegate" source="org.nevis.
cairngorm.samples.login.LoginDelegate"
result="event.call.resultHandler( event )"
fault="event.call.faultHandler( event )">
</mx:RemoteObject>
</cairngorm:ServiceLocator>
This is the way that you subclass a class in flex. but does flex
really create a class that inherits from ServiceLocator class or does
it create something else which "somehow" copies the code from
ServiceLocator class and create a new class with a property of
RemoteObject ?
if it is really subclassing, then in your code, when you do
public function CustomerListDelegate ( responder : Responder )
{
this.service = ServiceLocator.getInstance().getService("
roCustList");
this.responder = responder;
}
ServiceLocator.getInstance() should return a reference to the parent
class, not child class. Then how can you use getService() function to
return a reference to the remoting object? the Parent class "
ServiceLocator" defined in cairngorm does not have a property of
RemoteObject. It's the child class that we created using MXML has a
property of remoteObject.
I'm sorry for making this confusing and complicated. I just want to
know how the framework really works.
Thanks for the help again,
Larry
--- In flexcoders@yahoogroups.com, [EMAIL PROTECTED] wrote:
>
> Are you creating a business delegate class to handle the service
call? In
> the cairngorm framework, the actual work of getting the
remoteObject and
> making a request is inside a delegate. Consider, for example a
> remoteObject service which returns a list of customers with the id:
> "roCustList". Create a business delegate class called
> 'CustomerListDelegate' having this function:
>
> public function CustomerListDelegate ( responder : Responder )
> {
> this.service = ServiceLocator.getInstance().getService("
roCustList");
> this.responder = responder;
> }
>
> the call is made here:
>
> public function getCustList(): void
> {
> var call : Object = service.getCustList();
> call.resultHandler = responder.onResult;
> call.faultHandler = responder.onFault;
> }
>
> Obviously there is much more to creating a successful request/
response to a
> service call than this. You have to create a cairngorm event and
dispatch
> that event with is handled in a command class that places the
result in a
> model. I can send you a step-by-step bare bones example of all the
> required steps if you think you might benefit. I don't mind
admitting that
> I found it a bit bewildering at first, but when you get the hang of
it, it
> is a great framework.
>
>
>
>
>
>
> "Larry Liang" To: flexcoders@
yahoogroups.com
> <[EMAIL PROTECTED]>
cc:
> Sent by: Subject: [
flexcoders] How to subclass a singleton class ----
> flexcoders@yahoogroups.com cairngorm issue --
- Please help!!
> 04/27/2006 12:36
AM
> Please respond
to
>
flexcoders
>
>
>
>
>
>
>
> I'm new to Flex and have been spending a lot of time trying to
figure
> out how is part of cairngorm framework works. Please help.
>
> Cairngorm uses singleton pattern to ensure that there is only one
> instance of a class running for each app.
>
> For example, the ServiceLocator class use a static method to return
> the instance reference to you.
>
> public static function getInstance() : ServiceLocator
> {
> if ( serviceLocator == null )
> serviceLocator =
new
> ServiceLocator();
>
> return serviceLocator;
> }
>
> The documentation said that the recommended way to use this class is
> to subclass ServiceLocator and define your services, using the code
> similar to the following:
>
> <cairngorm:ServiceLocator xmlns:mx="http://www.macromedia.com/2003/
> mxml" xmlns:cairngorm="org.nevis.cairngorm.business.*" >
>
> <mx:RemoteObject id="customerDelegate" source="org.nevis.
> cairngorm.samples.login.LoginDelegate"
> result="event.call.resultHandler( event )"
> fault="event.call.faultHandler( event )">
> </mx:RemoteObject>
>
> </cairngorm:ServiceLocator>
>
> so far so good. however the documentation said Services can later be
> located, usually in a business delegate class as shown here:
> var service = ServiceLocator.getInstance().getService( "
> customerDelegate" );
>
> This is where I am confused. I just used mxml to subclass the
> servicelocator class and add a new property (remoteobject) to the
> instance of the subclass (not parent class). But when I use
> ServiceLocator.getInstance("cusomerDelegate")
>
> what I get is a reference to the parent class which is "
ServiceLocator
> " class defined by cairngorm. How can i use a reference to the
parent
> class to locate a property of the child class.
>
> I'm very confused. This may have something to do with the way that
> mxml script is compiled into actionscript object. Someone please
give
> me some ideas.
>
> By the way, I tried to subclass the ServiceLocator class in
> actionscript 2 and assign an service object to the subclass.
>
> When I use
>
> ServiceLocator.getInstance.getService('myService');
>
> The program returned saying that the service can not be found. I
> guess it kind of makes sense in that the object belongs to the
> subclass not the parent class.
>
> sorry for making this a bit long.
>
> Thanks,
>
> Larry
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> --
> Flexcoders Mailing List
> FAQ: http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.
txt
> Search Archives: http://www.mail-archive.com/flexcoders%40
yahoogroups.com
> Yahoo! Groups Links
>
>
>
>
>
>
>
>
>
>
>
>
> --------------------------------------------------------------------
-------
> This e-mail message (including attachments, if any) is intended for
the use
> of the individual or entity to which it is addressed and may contain
> information that is privileged, proprietary , confidential and
exempt from
> disclosure. If you are not the intended recipient, you are
notified that
> any dissemination, distribution or copying of this communication is
> strictly prohibited. If you have received this communication in
error,
> please notify the sender and erase this e-mail message immediately.
> --------------------------------------------------------------------
-------
>
--
Flexcoders Mailing List
FAQ: http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt
Search Archives:
http://www.mail-archive.com/flexcoders%40yahoogroups.com
Yahoo! Groups Links
--
Flexcoders Mailing List
FAQ: http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt
Search Archives: http://www.mail-archive.com/flexcoders%40yahoogroups.com
YAHOO! GROUPS LINKS
- Visit your group "flexcoders" on the web.
- To unsubscribe from this group, send an email to:
[EMAIL PROTECTED]
- Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
