Hrm... good point. Typicaly this:
function test()
{
a = new String();
}
test();
test();
Will cause the first created a to be destroyed & replaced with a new one. I
reckon the old one is marked for garbage collection.
However, "think" is dangerous. I can see how for 99% of the use cases you'd
want a Delegate to be a singleton to be utilized from a command, so that
makes perfect sense; good idea!
----- Original Message -----
From: "Tim Hoff" <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Monday, April 17, 2006 1:23 PM
Subject: [flexcoders] Re: Cairngorm2 Commands and Singletons
That's what I thought Jester. So the problem is not with the
commands but rather with the delegates. The samples provided
similar code to this:
var delegate : GetAuthorsDelegate = new GetAuthorsDelegate();
I'll make these singletons and see if that clears up the problem.
Thanks,
- TH
--- In [email protected], "JesterXL" <[EMAIL PROTECTED]> wrote:
>
> Cairngorm at start up creates a single instance of a command class
at start
> up.
>
> ARP, another framework like Cairngorm, creates an instance of a
command when
> it's called.
>
> Multiple calls to a Cairngorm command via EventBroacaster use the
same
> Command instance.
>
> Multiple calls to an ARP command via EventBroacaster use a new
Command
> instance.
>
> While I've been told Commands should be stateless, I disagree.
Since you
> can't block in Flash Player and everything is asyncronous, I think
Commands
> should have some form of state, even if this state is internal,
and is
> merely in the form of callback functions that it only uses for
itself (aka
> private).
>
> That said, Cairngorm's low-level design clearly believes and
encourages
> stateless Commands since only 1 instance of a Command class every
exists.
>
> Cairngorm keeps a reference to the Command class instances, so
they don't
> really ever go out of scope because they are kept internally in
the commands
> array.
>
> I know that's not a solution, just information, but figured
important
> nonetheless.
>
> ----- Original Message -----
> From: "Tim Hoff" <[EMAIL PROTECTED]>
> To: <[email protected]>
> Sent: Monday, April 17, 2006 12:46 PM
> Subject: [flexcoders] Cairngorm2 Commands and Singletons
>
>
> Apparently, there has been much discussion concerning singletons
> here already, but the search feature of this site doesn't seem to
> ever return complete results. Coming from a .NET background, I've
> had to change a lot my thinking in regards to objects. This is a
> good thing. However, in .NET (VB.NET, C#.NET Java.NET) when an
> object is instantiated, let's say a class in this case, as soon as
> the object goes out of scope, it is automatically disposed of by
the
> garbageCollector. This doesn't seem to be the case in AS3. I've
> patterned an application on the Cairngorm samples that have been
> provided so far. The samples are great and I really appreciate
> them, but none of them make multiple calls to the back-end. Using
> the code provided, if I execute multiple search commands (let's say
> getAuthors), each one of the command instances, along with the
> associated event listeners and objects, still exist after the
result
> or fault is returned. Thus, when an error is displayed
> like: "Sorry, no authors found.", since all of the
> commands/delegates are still listening to the data service, a
> separate alert box appears for each instance of the command. Three
> calls, three alert boxes.
>
> I'm not sure if I should make the commands and delegates
singletons,
> or manually dispose (delete _oSingleton) of the instances. Since
> the application is Cairngorm based, I don't want to stray too far
> from best practices. I was just wondering if anyone else had
> experienced this problem and if there were some links or advice
that
> could be offered? I also want to say that I think that the Adobe
> team is doing a great job. I can't wait for the release of Flex2.
> It's going to turn a lot of heads.
>
> Many thanks,
> Tim Hoff
>
> P.S. It would be nice to have something like the following:
>
> public singleton class myClass {}
>
>
>
>
>
>
>
>
> --
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