RE: [flexcoders] Re: Singleton not usable?
Thanks Tim,
I should not have been so brief in my original reply. I didn't mean to
imply that a implementing a Singleton is not possible in ActionScript,
only that you can't rely on the default access specifier to make your
constructor private, as you can in C#.
In ActionScript 3.0, the default access specifier for most class members
is "internal". The constructor is the exception, and is "public" whether
or not you include that keyword in the declaration.
Francis
> -Original Message-
> From: flexcoders@yahoogroups.com [mailto:[EMAIL PROTECTED]
On
> Behalf Of turbo_vb
> Sent: Friday, April 14, 2006 11:57 PM
> To: flexcoders@yahoogroups.com
> Subject: [flexcoders] Re: Singleton not usable?
>
> This a modified version of Jeff Tapper's singleton DataManager
> class for AS3 web service calls. Francis, note the private class
> constuctor at the bottom. Sorry about the jagged alignment.
>
> - Tim Hoff
>
>
> package code.business {
>
> import mx.managers.CursorManager;
> import flash.events.EventDispatcher;
> import mx.rpc.soap.WebService;
> import mx.rpc.events.ResultEvent;
> import mx.rpc.events.FaultEvent;
> import mx.rpc.AbstractOperation;
> import mx.controls.Alert;
> import flash.util.*;
>
> public class DataServices extends EventDispatcher {
> private var ws:WebService;
> private static var instanceMap:Object = new Object();
> public function DataServices(pri:PrivateClass, wsdl:String)
> {
> this.ws = new WebService();
> ws.wsdl = wsdl;
> ws.loadWSDL();
> ws.useProxy = false;
> }
> public static function getDataService
> (wsdl:String):DataServices
> {
> if(DataServices.instanceMap[wsdl] == null)
> {
> DataServices.instanceMap[wsdl] = new DataServices
> (new PrivateClass(),wsdl);
> }
>
> var ds:DataServices =
DataServices.instanceMap[wsdl];
> if(ds.ws.canLoadWSDL())
> {
> return ds;
> } else {
> throw new Error("BAD WSDL:"+wsdl);
> }
> }
> public function makeRemoteCall
> (methodName:String,showBusyCursor:Boolean,args:Object):void
> {
> var op:mx.rpc.AbstractOperation = ws[methodName];
> if(showBusyCursor)
> {
> CursorManager.setBusyCursor();
> }
> ws.addEventListener("result",onResult);
> ws.addEventListener("fault",onFault);
> if(args)
> {
> op.arguments = args;
> }
> op.send();
>
> }
> private function onResult(result:ResultEvent):void
> {
> CursorManager.removeBusyCursor();
> this.dispatchEvent(result);
> }
> private function onFault(fault:FaultEvent):void
> {
> CursorManager.removeBusyCursor();
> this.dispatchEvent(fault);
> }
> public override function toString():String
> {
> return "DataServices";
> }
> }
> }
>
> /** PrivateClass is used to make DataServices constructor private
> */
> class PrivateClass
> {
> public function PrivateClass() {}
> }
>
>
>
>
>
> --- In flexcoders@yahoogroups.com, "Francis Cheng" <[EMAIL PROTECTED]>
> wrote:
> >
> > That works in C# because the default access specifier for class
> members
> > in C# is private. It won't work in ActionScript 3.0 because the
> > constructor is always public, whether or not you declare it as
> such.
> >
> > Francis
> >
> > > -Original Message-
> > > From: flexcoders@yahoogroups.com
> [mailto:[EMAIL PROTECTED]
> > On
> > > Behalf Of crnet_flex
> > > Sent: Friday, April 14, 2006 3:19 PM
> > > To: flexcoders@yahoogroups.com
> > > Subject: [flexcoders] Re: Singleton not usable?
> > >
> > >
> > > Hi
> > >
> > > Have anyone tried using a construction like the following?
> > >
> > > public class Singleton
> > > {
> > > public static const Instance:Singleton = new Singleton();
> > >
> > > function Singleton()
> > > {
> > > }
> > >
> > > public function doSomething():void
> > > {
> > > }
> > > }
>
RE: [flexcoders] Re: Singleton not usable?
We've had other singleton discussions before so I won't re-hash, but
will point out that we don't have the same thread/locking problem that
Java does when accessing the singleton because your AS code is
single-threaded. So doing the if (instance == null) instance = new...
is just fine.
Matt
-Original Message-
From: flexcoders@yahoogroups.com [mailto:[EMAIL PROTECTED] On
Behalf Of crnet_flex
Sent: Friday, April 14, 2006 3:19 PM
To: flexcoders@yahoogroups.com
Subject: [flexcoders] Re: Singleton not usable?
--- In flexcoders@yahoogroups.com, "Sonja Duijvesteijn"
<[EMAIL PROTECTED]> wrote:
>
> Hi all,
>
> I'm trying to make a singleton class as demonstrated below, but
get the
> error: "a constructor may only be declared 'public'". Well, that
error is
> clear, the reason for it is not however.
> Isn't it possible anymore to make a singleton class, or is there
another
> method for it?
>
> Class Singleton {
>
> private static var _instance:Singleton = null;
>
> private function Sinleton() {
> }
>
> public static function getInstance():Singleton {
>if(Singleton._instance == null) {
> _instance = new Singleton();
>}
>return _instance;
> }
>
> }
>
> Any help would be much appreciated.
>
> Kind regards,
> Sonja Duijvesteijn
>
Hi
Have anyone tried using a construction like the following?
public class Singleton
{
public static const Instance:Singleton = new Singleton();
function Singleton()
{
}
public function doSomething():void
{
}
}
This is actually the recommandations of creating a singleton in c#,
and it seems that it fullfils the job here as well.
I know that, if you use flexbuilder 2 beta, then you'll get a
warning if you leave out the scope of the constructor, but maybe
it's worth it.
By the way, be aware that the singleton posted initially as an
example is not a recommended way of creating a singleton, i guess
it's not a problem in AS3, but lazy loaded singletons must have a
syncronized/looked load section when thread safety is an issue.
BR Casper
--
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[flexcoders] Re: Singleton not usable?
This a modified version of Jeff Tapper's singleton DataManager
class for AS3 web service calls. Francis, note the private class
constuctor at the bottom. Sorry about the jagged alignment.
- Tim Hoff
package code.business {
import mx.managers.CursorManager;
import flash.events.EventDispatcher;
import mx.rpc.soap.WebService;
import mx.rpc.events.ResultEvent;
import mx.rpc.events.FaultEvent;
import mx.rpc.AbstractOperation;
import mx.controls.Alert;
import flash.util.*;
public class DataServices extends EventDispatcher {
private var ws:WebService;
private static var instanceMap:Object = new Object();
public function DataServices(pri:PrivateClass, wsdl:String)
{
this.ws = new WebService();
ws.wsdl = wsdl;
ws.loadWSDL();
ws.useProxy = false;
}
public static function getDataService
(wsdl:String):DataServices
{
if(DataServices.instanceMap[wsdl] == null)
{
DataServices.instanceMap[wsdl] = new DataServices
(new PrivateClass(),wsdl);
}
var ds:DataServices = DataServices.instanceMap[wsdl];
if(ds.ws.canLoadWSDL())
{
return ds;
} else {
throw new Error("BAD WSDL:"+wsdl);
}
}
public function makeRemoteCall
(methodName:String,showBusyCursor:Boolean,args:Object):void
{
var op:mx.rpc.AbstractOperation = ws[methodName];
if(showBusyCursor)
{
CursorManager.setBusyCursor();
}
ws.addEventListener("result",onResult);
ws.addEventListener("fault",onFault);
if(args)
{
op.arguments = args;
}
op.send();
}
private function onResult(result:ResultEvent):void
{
CursorManager.removeBusyCursor();
this.dispatchEvent(result);
}
private function onFault(fault:FaultEvent):void
{
CursorManager.removeBusyCursor();
this.dispatchEvent(fault);
}
public override function toString():String
{
return "DataServices";
}
}
}
/** PrivateClass is used to make DataServices constructor private
*/
class PrivateClass
{
public function PrivateClass() {}
}
--- In flexcoders@yahoogroups.com, "Francis Cheng" <[EMAIL PROTECTED]>
wrote:
>
> That works in C# because the default access specifier for class
members
> in C# is private. It won't work in ActionScript 3.0 because the
> constructor is always public, whether or not you declare it as
such.
>
> Francis
>
> > -Original Message-
> > From: flexcoders@yahoogroups.com
[mailto:[EMAIL PROTECTED]
> On
> > Behalf Of crnet_flex
> > Sent: Friday, April 14, 2006 3:19 PM
> > To: flexcoders@yahoogroups.com
> > Subject: [flexcoders] Re: Singleton not usable?
> >
> >
> > Hi
> >
> > Have anyone tried using a construction like the following?
> >
> > public class Singleton
> > {
> > public static const Instance:Singleton = new Singleton();
> >
> > function Singleton()
> > {
> > }
> >
> > public function doSomething():void
> > {
> > }
> > }
> >
> > This is actually the recommandations of creating a singleton in
c#,
> > and it seems that it fullfils the job here as well.
> >
> > I know that, if you use flexbuilder 2 beta, then you'll get a
> > warning if you leave out the scope of the constructor, but maybe
> > it's worth it.
> >
> > By the way, be aware that the singleton posted initially as an
> > example is not a recommended way of creating a singleton, i guess
> > it's not a problem in AS3, but lazy loaded singletons must have a
> > syncronized/looked load section when thread safety is an issue.
> >
> > BR Casper
>
--
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RE: [flexcoders] Re: Singleton not usable?
That works in C# because the default access specifier for class members
in C# is private. It won't work in ActionScript 3.0 because the
constructor is always public, whether or not you declare it as such.
Francis
> -Original Message-
> From: flexcoders@yahoogroups.com [mailto:[EMAIL PROTECTED]
On
> Behalf Of crnet_flex
> Sent: Friday, April 14, 2006 3:19 PM
> To: flexcoders@yahoogroups.com
> Subject: [flexcoders] Re: Singleton not usable?
>
>
> Hi
>
> Have anyone tried using a construction like the following?
>
> public class Singleton
> {
> public static const Instance:Singleton = new Singleton();
>
> function Singleton()
> {
> }
>
> public function doSomething():void
> {
> }
> }
>
> This is actually the recommandations of creating a singleton in c#,
> and it seems that it fullfils the job here as well.
>
> I know that, if you use flexbuilder 2 beta, then you'll get a
> warning if you leave out the scope of the constructor, but maybe
> it's worth it.
>
> By the way, be aware that the singleton posted initially as an
> example is not a recommended way of creating a singleton, i guess
> it's not a problem in AS3, but lazy loaded singletons must have a
> syncronized/looked load section when thread safety is an issue.
>
> BR Casper
--
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
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/flexcoders/
<*> To unsubscribe from this group, send an email to:
[EMAIL PROTECTED]
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
[flexcoders] Re: Singleton not usable?
--- In flexcoders@yahoogroups.com, "Sonja Duijvesteijn"
<[EMAIL PROTECTED]> wrote:
>
> Hi all,
>
> I'm trying to make a singleton class as demonstrated below, but
get the
> error: "a constructor may only be declared 'public'". Well, that
error is
> clear, the reason for it is not however.
> Isn't it possible anymore to make a singleton class, or is there
another
> method for it?
>
> Class Singleton {
>
> private static var _instance:Singleton = null;
>
> private function Sinleton() {
> }
>
> public static function getInstance():Singleton {
>if(Singleton._instance == null) {
> _instance = new Singleton();
>}
>return _instance;
> }
>
> }
>
> Any help would be much appreciated.
>
> Kind regards,
> Sonja Duijvesteijn
>
Hi
Have anyone tried using a construction like the following?
public class Singleton
{
public static const Instance:Singleton = new Singleton();
function Singleton()
{
}
public function doSomething():void
{
}
}
This is actually the recommandations of creating a singleton in c#,
and it seems that it fullfils the job here as well.
I know that, if you use flexbuilder 2 beta, then you'll get a
warning if you leave out the scope of the constructor, but maybe
it's worth it.
By the way, be aware that the singleton posted initially as an
example is not a recommended way of creating a singleton, i guess
it's not a problem in AS3, but lazy loaded singletons must have a
syncronized/looked load section when thread safety is an issue.
BR Casper
--
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
<*> To visit your group on the web, go to:
http://groups.yahoo.com/group/flexcoders/
<*> To unsubscribe from this group, send an email to:
[EMAIL PROTECTED]
<*> Your use of Yahoo! Groups is subject to:
http://docs.yahoo.com/info/terms/
