I just wanted to follow
up in case my last post wasnt totally clear. JesterXL
said:
> > I usually do:
> >
>
> dispatchEvent({type: "someEvent", target:
this});
What I wanted to make
sure I pointed out is that Flex will set the target property to this (the
object calling dispatchEvent) when the event gets broadcast, overwriting any
value you may set. So although this actually shows up in some of the doc
examples, dont do it, it doesnt work it may have seemed to work, but only
coincidentally because this is generally what you
want.
You know, I also find
the behavior not exactly intuitive because of semantic reasons. If you think of
target as meaning the component upon which an event occurred, then this value
should be preserved up the chain; in any case, I think target is a poor naming
choice. An event broadcaster is a source, like in Java, or something along
those lines. For a listener receiving a notification, source ought to point to
the broadcasting object, even if it is just a middle link in what is a chain of
listeners. Target should be a value that refers to a component and is set only
once and preserved up the chain.... Or something along these
lines
.
;-)
Tony
tony pujals| senior
engineer | Yahoo! SiteBuilder
p. 408.349.6284
| e. [EMAIL PROTECTED] | y!id
tonypujals
From:
Tony Pujals
Sent: Wednesday, November 23, 2005 11:06
AM
To: 'flexcoders@yahoogroups.com'
Subject: RE: [flexcoders] event bubbling
Flex 1.5
So funny this thread
just caught my eye because I just had to deal with the very same
issue.
When you call
dispatchEvent, the target property is always overridden. Although I have seen a
few erroneous examples, the docs tell you not to set the target property in the
event object because it will be explicitly set to refer to the object that is
dispatching the event. Therefore, the original target will be
lost.
I bubble up my events
through chaining (for example, a ThemeManager that propagates theme changes that
propagates scheme changes that propagates individual style (font and color)
changes), but I preserve the original event with a rootEvent property. The chain
of handlers continue to add this property to the new event that is getting
dispatched up the chain, preserving the value that each listener
receives.
I should point out that
athough preserving the original event is useful, each listener in the chain
generally needs to add other context aside from just bubbling up the original
event. The ultimate listener cant do much with the rootEvent object (eg, a font
style), without the additional context added by the listeners in the change (for
example, current theme : page title scheme : new font
style).
-Tony
tony pujals| senior
engineer | Yahoo! SiteBuilder
p. 408.349.6284
| e. [EMAIL PROTECTED] | y!id
tonypujals
From:
flexcoders@yahoogroups.com
[mailto:flexcoders@yahoogroups.com]
On Behalf Of Douglas
Knudsen
Sent: Wednesday,
November 23, 2005 10:37 AM
To:
flexcoders@yahoogroups.com
Subject: Re: [flexcoders] event bubbling
Flex 1.5
helps to actually attach the file,
eh? sorry about the traffic...I
need some of that coffee now too
Jesse.
DK
On
11/23/05, Douglas Knudsen <[EMAIL PROTECTED]>
wrote:
>
lol!
>
> Ok, I attached a sample in a zip, hope it stays
attached. In it I
> have a
A, B, C as an example of this thread discussion. You can
see
> that the final capture of
the event in A loses the original target.
> upon a suggestion elsewhere, I tried 'chaining' the
events by catching
> the event in
B and re-dispatching it. This still messed with
the
> target property of the
event object. Seems have to add this as a
> extra property in the original
event.
>
> Jeff, looking at your evenmanger class now to see if I
can use this.
>
>
DK
>
> On 11/23/05, JesterXL <[EMAIL PROTECTED]>
wrote:
> > ...er, sorry,
C. 2nd cup of coffee hasn't kicked in...
> >
>
> ----- Original Message -----
> > From: "JesterXL"
<[EMAIL PROTECTED]>
> > To: <flexcoders@yahoogroups.com>
> > Sent: Wednesday, November 23, 2005 12:09
PM
> > Subject: Re:
[flexcoders] event bubbling Flex 1.5
> >
>
>
> > I usually
do:
>
>
> > dispatchEvent({type:
"someEvent", target: this});
>
>
> > Where this points to
the component dispatching the event. So, if A wants
to
> > know who dispatched the
event:
>
>
> > function
someEvent(o)
> >
{
> >
trace(o.target); // this is A
>
> }
>
>
> > ----- Original
Message -----
> > From:
"Douglas Knudsen" <[EMAIL PROTECTED]>
> > To: <flexcoders@yahoogroups.com>
> > Sent: Wednesday, November 23, 2005 11:52
AM
> > Subject: Re:
[flexcoders] event bubbling Flex 1.5
> >
>
>
> > drat! I read
your blog entry on this too, forgot about it. Ok,
in
> > my scenario below, I
have A catching the event dispatched in C. But
> > the target in the event still points to B the
middleman. I need A to
>
> be able to be able to reference C in the event. Is the only way
to
> > add a reference to C in
the event dispatch in C?
>
>
> >
DK
>
>
> > On 11/23/05, JesterXL
<[EMAIL PROTECTED]> wrote:
> > > It IS supported:
> > > http://www.jessewarden.com/archives/2005/11/event_bubbling.html
> > >
> > > ----- Original Message
-----
> > > From: "Douglas
Knudsen" <[EMAIL PROTECTED]>
> > > To: <flexcoders@yahoogroups.com>
> > > Sent: Wednesday, November 23, 2005 11:29
AM
> > > Subject:
[flexcoders] event bubbling Flex 1.5
> > >
> > >
> > > not supportted I know, how to work
around?. Say I have 3 components
> > > A,B, and C. B is a child of A and C is a
child of B, each child among
>
> > children possibly. Now, if C fires an event called
fooEvent, I can
> > > get A
to catch it, but the event.target points to B not C. The way
I
> > > worked around this
was in B I caught the event then re-broadcast it so
> > > that A could catch it. In the
re-broadcast I added a reference to C
> > > in the event. How else can I 'bubble' up
an event?
> >
>
> >
>
> > >
--
> > > Douglas
Knudsen
> > > http://www.cubicleman.com
> > > this is my signature, like
it?
> >
>
> >
>
> >
>
> > >
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