RE: [flexcoders] Re: Dispatching multiple events in order with cairngorm

Thu, 01 Jun 2006 12:35:18 -0700

Tim,

That's the one part of Cairngorm (for me) that's the tricksiest... how one
might handle (as someone else recently put it) the sexy features of Flex in
Cg.  Transitions, states, effects, animations that may need to be
syncronized with something else.  Of course, you don't want to put too much
control in the Cg framework since that might restrict you in some other way
(I definitely agree that Cg needs to be lightweight as Steven's articles
point out.)  The ChangeWatcher is, however, very cool in that it allows you
to watch not only one bound state value, but chains of them... so if you
needed to trigger an event only after, say, four other events completed you
could have those four events set flags in the ModelLocator on effectEnd and
have your ChangeWatcher bound to all four flags, only calling it's handler
after all four were completed.  I think that the ChangeWatcher is a great
addition to B3, and actually offers the same benefits, with more
functionality, than Paul's helper class.  As far as Cg goes, maybe we just
need a Cg example out there that uses ChangeWatcher (or something like it)
that shows a chain of events triggering a final command... take some of the
mystery out of it.

Darren



>From: "Tim Hoff" <[EMAIL PROTECTED]>
>Reply-To: [email protected]
>To: [email protected]
>Subject: [flexcoders] Re: Dispatching multiple events in order with
>cairngorm
>Date: Thu, 01 Jun 2006 16:42:55 -0000
>
>I absolutely agree that a Command should never invoke anything view
>related, except for setting bound model values that update views
>automatically.  For Jean-Luc's scenario, my thinking is that there
>may be several different views that require closure before the
>primary command is executed.  To close any or all of the
>possible open views in a clean and synchronous manner, I would think
>that you could combine the SequenceCommand (is it ChainCommand now?)
>with the ChangeWatcher utility or a simple eventListener.  The
>executeNextCommand function would be invoked only after the
>SequenceCommand receives notification of the effectEnd event. The
>question is, should you use the ChangeWatcher to listen for a model
>variable change, that would have to be updated by the view or a
>helper?   Or, would an explicit eventListener for the views'
>effectEnd event be more suitable?
>
>This is a gray area in Cairngorm for me.  It seems that there may be
>times when a complete round-trip of event communication, starting
>and ending at a view, may come in handy and/or be necessary.  Well,
>maybe not necessary but certainly more convenient.  For me, this
>fits in the same category as deciding whether to perform a simple
>view action with a ViewHelper/ViewLocator or with yet another
>Event/Control/Command/Model structure.   I'm not sure if discussing
>theoretical framework implementation is germane to this list, but
>I'd be interested to hear further thoughts (best practices)
>concerning this topic.  Thanks for your ideas Steven, Alex and
>Darren.
>
>Tim Hoff
>
>
>--- In [email protected], "Jean-Luc ESSER" <[EMAIL PROTECTED]> wrote:
> >
> > I do agree with you guys, that's the way to go !
> > Thanx !
> >
> > BTW, loved Paul's little helper.
> > This one is a sure hit !
> >
> > -JL
> >
> > ----- Original Message -----
> > From: "Darren Houle" <[EMAIL PROTECTED]>
> > To: <[email protected]>
> > Sent: Thursday, June 01, 2006 4:49 PM
> > Subject: RE: [flexcoders] Re: Dispatching multiple events in order
>with
> > cairngorm
> >
> >
> > >I agree with Alex.  Say you have a View with a button... you
>mutate that
> > > button's click="" event into a CairngormEvent.  Your custom Cg
>Event
> > > triggers a Cg Command, which sets state in the ModelLocator.
>New to Beta
> > > 3
> > > is a utility called ChangeWatcher that allows you to watch a
>bindable
> > > value
> > > and define a handler to run when the value changes.  In the
>original View
> > > (or any other View) you could simply watch that state var and
>have
> > > ChangeWatcher call yourMoveEffect.play().  You could mutate the
>standard
> > > effectEnd="" event into a new CairngormEvent that triggered the
>Cg Command
> > > that needs to run at the end of the effect.
> > >
> > > Darren
> > >
> > >
> > >
> > >>From: "Alex Uhlmann" <[EMAIL PROTECTED]>
> > >>Reply-To: [email protected]
> > >>To: <[email protected]>
> > >>Subject: RE: [flexcoders] Re: Dispatching multiple events in
>order with
> > >>cairngorm
> > >>Date: Thu, 1 Jun 2006 06:46:57 -0700
> > >>
> > >>Hi Guys,
> > >>
> > >>
> > >>I'd probably suggest letting the view dispatch a Cairngorm
>event, having
> > >>that following Command change a state in your model and have
>that view
> > >>bind to that state change in the model. This view will trigger
>the
> > >>effect and at effectEnd you will trigger another Command. IMHO,
>the
> > >>Command should never invoke anything view related (like an
>effect) by
> > >>himself.
> > >>
> > >>Note that your view (MXML) can bind to the model using the
>mx:Binding
> > >>tag. BTW: check out Paul's little helper for that.  ;)
> >
> >>http://weblogs.macromedia.com/paulw/archives/2006/05/the_worlds_sma
>l.cfm
> > >>#more
> > >>
> > >>
> > >>Best,
> > >>Alex
> > >>
> > >>Alex Uhlmann
> > >>Consultant (Rich Internet Applications)
> > >>Adobe Consulting
> > >>Westpoint, 4 Redheughs Rigg, South Gyle, Edinburgh, EH12 9DQ, UK
> > >>p: +44 (0) 131 338 6969
> > >>m: +44 (0) 7917 428 951
> > >>[EMAIL PROTECTED]
> > >>
> > >>
> > >>-----Original Message-----
> > >>From: [email protected]
>[mailto:[EMAIL PROTECTED] On
> > >>Behalf Of Jean-Luc ESSER
> > >>Sent: 01 June 2006 10:35
> > >>To: [email protected]
> > >>Subject: Re: [flexcoders] Re: Dispatching multiple events in
>order with
> > >>cairngorm
> > >>
> > >>Thanx Tim i'm gonna look into this, but i'm worried about one
>issue :
> > >>In case of a command launching an effect in a component, when
>the effect
> > >>starts, it means the command has executed, thus invocating the
>next
> > >>command.
> > >>What if i want to wait for effectEnd before invoking next
>command...
> > >>
> > >>I'll keep you posted.
> > >>
> > >>-JL, investigating.
> > >>
> > >>----- Original Message -----
> > >>From: "Tim Hoff" <[EMAIL PROTECTED]>
> > >>To: <[email protected]>
> > >>Sent: Thursday, June 01, 2006 11:18 AM
> > >>Subject: [flexcoders] Re: Dispatching multiple events in order
>with
> > >>cairngorm
> > >>
> > >>
> > >> > Hi Jean-Luc,
> > >> >
> > >> > It looks like you might need to use the Cairngorm
>SequenceCommand
> > >> > class.  I haven't used this yet but if you look at the source
>for the
> > >> > SequenceCommand class, it describes a possible solution for
>you.  If
> > >> > you use this and get it to work, please post your findings
>here.
> > >> >
> > >> > Good Luck,
> > >> > Tim
> > >> >
> > >> >
> > >> > --- In [email protected], "JL E." <flex@> wrote:
> > >> >>
> > >> >> Hi there !
> > >> >>
> > >> >> I have a search pane. I open it (sliding to the right).
> > >> >> Now, i want to go somewhere else in the application.
> > >> >> In order to do that, when clicking on let's say 'contact', i
> > >> > dispatch an event which is gonna show page contact.
> > >> >> The thing is that when clicking 'contact', before executing
>the
> > >> > command which is gonna build contact page, i want to check if
>the
> > >> > search pane is open, and if so, i want to dispatch event
> > >> > closeSearchPane, wait until it is fully closed, and only then
>execute
> > >> > my command showContactPage.
> > >> >> I guess coding this logic in my command showContactPage won't
> > >> > scale as i may need this logic to work everywhere in the app,
> > >> > whichever event i am gonna dispatch.
> > >> >> How would you do it ? What am i missing here ?
> > >> >>
> > >> >> Best,
> > >> >> Jean-Luc
> > >> >>
> > >> >> PS: Thanx Alex for previous answers regarding getters
>setters !
> > >> > Worked fine !
> > >> >>
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >> >
> > >> > --
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