[flexcoders] Flex/Cairngorm Syntax
HiI am just embarking on my first Cairngorm based Flex app. In one of the sample apps there is the following syntaxpublic function onResult(event:* = null):void{}Could somebody please explain exactly what the argument "(event:* = null)" is actually doing. Obviously the argument is called 'event', I have got that far. Is the asterisk a wildcard for the type, and if so why, and is the null a default value if the argument is not supplied?I have had a look around the web and the docs but can't find any explanation of this syntax. What is more, I am not getting it to work but as I don't understand what it is supposed to be I'm not sure where the problem lies.Thanks for your help in advance...Graham
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Re: [flexcoders] Flex/Cairngorm Syntax
Hi Graham,
you're exactly right, * is a wildcard, meaning the parameter event
that is passed to the function, can be of any type. By default, if not
passed in, it is assumed NULL. This also is written somewhere in the
docs but at the moment, I can'T remember where it was.
Cheers, Thomas
Thomas Rühl
Design, Programming Concepts
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grahampengelly wrote:
Hi
I am just embarking on my first Cairngorm based Flex app. In one of
the sample apps there is the following syntax
public function onResult(event:* = null):void
{
}
Could somebody please explain exactly what the argument (event:* =
null) is actually doing. Obviously the argument is called 'event', I
have got that far. Is the asterisk a wildcard for the type, and if so
why, and is the null a default value if the argument is not supplied?
I have had a look around the web and the docs but can't find any
explanation of this syntax. What is more, I am not getting it to work
but as I don't understand what it is supposed to be I'm not sure where
the problem lies.
Thanks for your help in advance...
Graham
--
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RE: [flexcoders] Flex/Cairngorm Syntax
Graham
I see someone else answered your question, but... you might also want to
look at Darron's page which talks about the Cairngorm Responder vs the Flex
IResponder:
http://www.darronschall.com/weblog/archives/000234.cfm
The onResult(event:* = null):void method you asked about tells me you're
using/learning the pure Cairngorm architecture which employs a Cairngorm
Responder to get the data from the Delegate/Service back to the initial
Command. Darron's page explains an alternative, IResponder, that is already
part of the Flex API. It does the same thing, but it's more flexible,
simpler to use, and easier to understand (just my opinion). I'm using it in
all my new Cairngorm apps. I have yet to find a reason not to.
Darren
From: grahampengelly [EMAIL PROTECTED]
Reply-To: flexcoders@yahoogroups.com
To: flexcoders@yahoogroups.com
Subject: [flexcoders] Flex/Cairngorm Syntax
Date: Tue, 15 Aug 2006 13:02:35 -
Hi
I am just embarking on my first Cairngorm based Flex app. In one of the
sample apps there is the following syntax
public function onResult(event:* = null):void
{
}
Could somebody please explain exactly what the argument (event:* =
null) is actually doing. Obviously the argument is called 'event', I
have got that far. Is the asterisk a wildcard for the type, and if so
why, and is the null a default value if the argument is not supplied?
I have had a look around the web and the docs but can't find any
explanation of this syntax. What is more, I am not getting it to work
but as I don't understand what it is supposed to be I'm not sure where
the problem lies.
Thanks for your help in advance...
Graham
--
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FAQ: http://groups.yahoo.com/group/flexcoders/files/flexcodersFAQ.txt
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Re: [flexcoders] Flex/Cairngorm Syntax
Title: Re: [flexcoders] Flex/Cairngorm Syntax
The * is an approximation of the Object keyword. Can be any type. Im not sure whether the typing is preserved or not but im sure Matt can confirm this. In effect event is cast as any object rather than having a strongly typed function call. Be aware in doing this though as type coercion issues may occur later on when dealing with the result.
Since all event classes usually subclass from Event, you might use Event rather than * for type safety.
Regards
Samuel
On 15/8/06 15:02, grahampengelly [EMAIL PROTECTED] wrote:
Hi
I am just embarking on my first Cairngorm based Flex app. In one of the sample apps there is the following syntax
public function onResult(event:* = null):void
{
}
Could somebody please explain exactly what the argument (event:* = null) is actually doing. Obviously the argument is called 'event', I have got that far. Is the asterisk a wildcard for the type, and if so why, and is the null a default value if the argument is not supplied?
I have had a look around the web and the docs but can't find any explanation of this syntax. What is more, I am not getting it to work but as I don't understand what it is supposed to be I'm not sure where the problem lies.
Thanks for your help in advance...
Graham
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Re: [flexcoders] Flex/Cairngorm Syntax
Actually... in Cairngorm, if a Command implements Responder the Command
*must* contain:
public function onResult( event : * = null ) : void {}
public function onFault( event : * = null ) : void {}
...and if a Command implements IResponder that changes to
public function result( event : Object ) : void {}
public function fault( event : Object ) : void {}
So in Graham's case, if he's using vanilla Cairngorm 2.0 his Commands are
implemeting Responder, so he can't use Event in place of *... if he goes to
Cairngorm 2.01 (my numbering, not a real thing) and uses IResponder he can
use an Object type for the arg... but to use any other arg type (like event
: Event) the Command would need to implement some totally new Responder
class.
Darren
From: Samuel D. Colak [EMAIL PROTECTED]
Reply-To: flexcoders@yahoogroups.com
To: flexcoders@yahoogroups.com
Subject: Re: [flexcoders] Flex/Cairngorm Syntax
Date: Tue, 15 Aug 2006 18:52:07 +0200
The * is an approximation of the Object keyword. Can be any type. Im not
sure whether the typing is preserved or not but im sure Matt can confirm
this. In effect event is cast as any object rather than having a strongly
typed function call. Be aware in doing this though as type coercion issues
may occur later on when dealing with the result.
Since all event classes usually subclass from Event, you might use Event
rather than * for type safety.
Regards
Samuel
On 15/8/06 15:02, grahampengelly [EMAIL PROTECTED] wrote:
Hi
I am just embarking on my first Cairngorm based Flex app. In one of the
sample
apps there is the following syntax
public function onResult(event:* = null):void
{
}
Could somebody please explain exactly what the argument (event:* =
null) is
actually doing. Obviously the argument is called 'event', I have got
that far.
Is the asterisk a wildcard for the type, and if so why, and is the null
a
default value if the argument is not supplied?
I have had a look around the web and the docs but can't find any
explanation
of this syntax. What is more, I am not getting it to work but as I don't
understand what it is supposed to be I'm not sure where the problem
lies.
Thanks for your help in advance...
Graham
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RE: [flexcoders] Flex/Cairngorm Syntax
You can learn more about the * datatype
here: http://livedocs.macromedia.com/flex/2/docs/1826.html
Default parameters are described here: http://livedocs.macromedia.com/flex/2/docs/1834.html
HTH,
Matt
From:
flexcoders@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Samuel D. Colak
Sent: Tuesday, August 15, 2006
9:52 AM
To: flexcoders@yahoogroups.com
Subject: Re: [flexcoders]
Flex/Cairngorm Syntax
The * is an approximation of the
Object keyword. Can be any type. Im not sure whether the typing is preserved or
not but im sure Matt can confirm this. In effect event is cast as any object
rather than having a strongly typed function call. Be aware in doing this
though as type coercion issues may occur later on when dealing with the result.
Since all event classes usually subclass from Event, you might use Event rather
than * for type safety.
Regards
Samuel
On 15/8/06 15:02, grahampengelly [EMAIL PROTECTED]ultants.com
wrote:
Hi
I am just embarking on my first Cairngorm based Flex app. In one of the sample
apps there is the following syntax
public function
onResult(event:* = null):void
{
}
Could somebody please explain exactly what the argument
(event:* = null) is actually doing. Obviously the argument is
called 'event', I have got that far. Is the asterisk a wildcard for the type,
and if so why, and is the null a default value if the argument is not supplied?
I have had a look around the web and the docs but can't find any explanation of
this syntax. What is more, I am not getting it to work but as I don't
understand what it is supposed to be I'm not sure where the problem lies.
Thanks for your help in advance...
Graham
__._,_.___
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Search Archives: http://www.mail-archive.com/flexcoders%40yahoogroups.com
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Computer software development
Software design and development
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Software development best practice
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