And you're not getting "foo is not an IEventDispatcher"? What's your
DateRange class extend? It may already be an EventDispatcher. I left my
testbed code at work, so I can't verify it for myself :)
Most intriguing though.
-J
On Wed, May 21, 2008 at 3:54 PM, Richard Rodseth <[EMAIL PROTECTED]> wrote:
> I don't believe that's the case, Josh. I just ran it again, with
> [Bindable] on the start property, but not the end property, and got
> the warnings for end, but not for start.
>
>
> On Tue, May 20, 2008 at 10:30 PM, Josh McDonald <[EMAIL
> PROTECTED]<dznuts%40gmail.com>>
> wrote:
> > What you're doing there is just tricking the compiler into not giving you
> > the warning, but you'll still get a run-tiAme warning in your console.
> You
> > won't get updates if start ever changes, which in your case is what you
> > want- but if it's simply read-only rather than immutable, you'll need the
> > call to dispatchEvent().
> >
> > -J
> >
> > On Wed, May 21, 2008 at 3:21 PM, Richard Rodseth <[EMAIL
> > PROTECTED]<rrodseth%40gmail.com>>
> wrote:
> >>
> >> Interesting. Actually, I just did this:
> >>
> >> [Bindable(event="foo")]
> >> public function get start():Date {
> >> return _start;
> >> }
> >>
> >> without deriving from EventDispatcher (unnecessary, since I'm not
> >> dispatching anywhere), and that also worked. So perhaps that's the
> >> best approach, assuming the overhead of the [Bindable] tag is pretty
> >> minimal.
> >>
> >> Without knowing much about the internals, I can't be sure whether/how
> >> the warning could be more discriminating or informative, although I
> >> would think the runtime could tell that the property is read-only and
> >> not the root of the expression.
> >>
> >> Thanks.
> >>
> >> On Tue, May 20, 2008 at 9:43 PM, Josh McDonald <[EMAIL
> >> PROTECTED]<dznuts%40gmail.com>>
> wrote:
> >> > Binding to read-only accessors does work with custom events:
> >> >
> >> > ------------------- testbed.xml
> >> >
> >> > <?xml version="1.0" encoding="utf-8"?>
> >> > <mx:Application xmlns:mx="http://www.adobe.com/2006/mxml";
> >> > layout="absolute"
> >> > xmlns:ns1="*" >
> >> >
> >> > <ns1:TestBindings id="test"/>
> >> > <mx:Label text="Testbed number is { test.publicNumber }"
> >> > horizontalCenter="0" verticalCenter="0"/>
> >> >
> >> > <mx:Button label="Ouch!" horizontalCenter="0" verticalCenter="30"
> >> > click="test.doIt()"/>
> >> >
> >> > </mx:Application>
> >> >
> >> > ------------------- TestBed.as
> >> >
> >> > package
> >> > {
> >> > import flash.events.Event;
> >> > import flash.events.EventDispatcher;
> >> >
> >> > public class TestBindings extends EventDispatcher
> >> > {
> >> >
> >> > private var myNumber : Number = 10;
> >> >
> >> > public function doIt() : void {
> >> >
> >> > myNumber++;
> >> > dispatchEvent(new Event("numberUpdated"));
> >> > }
> >> >
> >> > [Bindable(event="numberUpdated")]
> >> > public function get publicNumber() : Number { return myNumber; }
> >> > }
> >> > }
> >> > -------------------
> >> >
> >> > This works as you'd expect it to, so it is possible to bind to
> read-only
> >> > (and therefore also to immutable, if that really floats your boat) so
> >> > long
> >> > as it's an IEventDispatcher.
> >> >
> >> > -J
> >> >
> >> > On Wed, May 21, 2008 at 2:34 PM, Alex Harui <[EMAIL
> >> > PROTECTED]<aharui%40adobe.com>>
> wrote:
> >> >>
> >> >> Yup, that's why it is a warning. Sometimes you can ignore it.
> >> >>
> >> >>
> >> >>
> >> >> ________________________________
> >> >>
> >> >> From: flexcoders@yahoogroups.com <flexcoders%40yahoogroups.com>[mailto:
> flexcoders@yahoogroups.com <flexcoders%40yahoogroups.com>] On
> >> >> Behalf Of Richard Rodseth
> >> >> Sent: Tuesday, May 20, 2008 9:11 PM
> >> >> To: flexcoders@yahoogroups.com <flexcoders%40yahoogroups.com>
> >> >> Subject: Re: [flexcoders] "unable to bind to property" warnings
> binding
> >> >> to
> >> >> read-only properties
> >> >>
> >> >>
> >> >>
> >> >> Message delivery failed. Trying again, this time with blog entry:
> >> >>
> >> >> http://flexygen.wordpress.com/2008/05/21/immutability-and-binding/
> >> >>
> >> >> On Tue, May 20, 2008 at 7:40 PM, Richard Rodseth <[EMAIL
> >> >> PROTECTED]<rrodseth%40gmail.com>
> >
> >> >> wrote:
> >> >> > Yes, but the point is that DateRange.start is not changeable - the
> >> >> > DateRange object can be replaced in its entirety, but its pieces
> can
> >> >> > not be changed.
> >> >> >
> >> >> > I was able to get rid of the warnings by creating bindable getters
> in
> >> >> > the component that used the expression, replacing the expression
> with
> >> >> > {this.start}.
> >> >> >
> >> >> > I've also verified that with the original expression {range.start}
> >> >> > the
> >> >> > binding works despite the warning.
> >> >> >
> >> >> > On Tue, May 20, 2008 at 4:56 PM, Alex Harui <[EMAIL
> >> >> > PROTECTED]<aharui%40adobe.com>>
> wrote:
> >> >> >> Unless DateRenge.start is bindable, then there's no way we'd be
> able
> >> >> >> to
> >> >> >> see
> >> >> >> changes to it.
> >> >> >>
> >> >> >>
> >> >> >>
> >> >> >> ________________________________
> >> >> >>
> >> >> >> From: flexcoders@yahoogroups.com
> >> >> >> <flexcoders%40yahoogroups.com>[mailto:
> flexcoders@yahoogroups.com <flexcoders%40yahoogroups.com>]
> >> >> >> On
> >> >> >> Behalf Of Richard Rodseth
> >> >> >> Sent: Tuesday, May 20, 2008 2:53 PM
> >> >> >> To: flexcoders@yahoogroups.com <flexcoders%40yahoogroups.com>
> >> >> >> Subject: Re: [flexcoders] "unable to bind to property" warnings
> >> >> >> binding
> >> >> >> to
> >> >> >> read-only properties
> >> >> >>
> >> >> >>
> >> >> >>
> >> >> >> Just when I think I understand binding....
> >> >> >>
> >> >> >> I believe I have the same issue described below. I have an
> immutable
> >> >> >> class DateRange. Surely, if I have
> >> >> >>
> >> >> >> [Bindable]
> >> >> >> public var range:DateRange;
> >> >> >>
> >> >> >> I should be able to have a binding expression
> "{model.range.start}"
> >> >> >> ?
> >> >> >>
> >> >> >> Thanks!
> >> >> >>
> >> >> >> On Thu, Jul 19, 2007 at 8:06 AM, mikebgrove <[EMAIL
> >> >> >> PROTECTED]<mikebgrove%40yahoo.com>
> >
> >> >> >> wrote:
> >> >> >>> i make extensive use of read-only properties in my ActionScript
> >> >> >>> code. i find that anywhere i try to bind to a read only property
> i
> >> >> >>> get a warning in flex builder's debug mode indicating that flex
> >> >> >>> can't
> >> >> >>> bind to the property.
> >> >> >>>
> >> >> >>> here's a simple class to illustrate the point.
> >> >> >>>
> >> >> >>> package
> >> >> >>> {
> >> >> >>> public class Foo
> >> >> >>> {
> >> >> >>> public function get bar():String {
> >> >> >>> return "bar";
> >> >> >>> }
> >> >> >>> }
> >> >> >>> }
> >> >> >>>
> >> >> >>> if foo is an [Bindable] instance of Foo, then a binding to
> >> >> >>> {foo.bar}
> >> >> >>> will produce this warning:
> >> >> >>>
> >> >> >>> warning: unable to bind to property 'bar' on class 'Foo' (class
> is
> >> >> >>> not an IEventDispatcher).
> >> >> >>>
> >> >> >>> Foo is not an IEventDispatcher, but since every property of Foo
> is
> >> >> >>> immutable it shouldn't need to be.
> >> >> >>>
> >> >> >>> this may be a flex defect, judging by the title of the defect at
> >> >> >>> http://bugs.adobe.com/jira/browse/SDK-1046. i've asked adobe
> >> >> >>> support
> >> >> >>> to make more details about this defect public.
> >> >> >>>
> >> >> >>> i'm interested in strategies to avoid this warning for read-only
> >> >> >>> properties. in some cases this warning is instrumental in helping
> >> >> >>> me
> >> >> >>> figure out a binding problem, but unfortunately the important
> >> >> >>> warnings are nearly impossible to find among the hundreds of
> >> >> >>> irrelevant warnings for binding to read-only properties.
> >> >> >>>
> >> >> >>> here are some of the strategies i can think of, none great (i'll
> >> >> >>> continue using the above Foo class as an example):
> >> >> >>>
> >> >> >>> 1) don't bind to {foo.bar}, bind to {getBar(foo)} or
> >> >> >>> {foo.getBar()},
> >> >> >>> adding the getBar method either to the MXML component trying to
> >> >> >>> bind
> >> >> >>> to foo or the Foo class itself.
> >> >> >>> 2) declare the bar getter function as [Bindable] to a made up
> event
> >> >> >>> name, e.g.
> >> >> >>> [Bindable(event="barChangedNeverGonnaHappen")]
> >> >> >>>
> >> >> >>> are there other strategies people have employed to eliminate
> these
> >> >> >>> warnings for read-only properties? i trust i'm not the only one
> >> >> >>> whose eclipse debug console has been consumed with warnings like
> >> >> >>> these.
> >> >> >>>
> >> >> >>> thanks.
> >> >> >>>
> >> >> >>> -mike
> >> >> >>>
> >> >> >>>
> >> >> >>
> >> >> >>
> >> >> >
> >> >
> >> >
> >> > --
> >> > "Therefore, send not to know For whom the bell tolls. It tolls for
> >> > thee."
> >> >
> >> > :: Josh 'G-Funk' McDonald
> >> > :: 0437 221 380 :: [EMAIL PROTECTED] <josh%40gfunk007.com>
> >> >
> >
> >
> >
> > --
> > "Therefore, send not to know For whom the bell tolls. It tolls for thee."
> >
> > :: Josh 'G-Funk' McDonald
> > :: 0437 221 380 :: [EMAIL PROTECTED] <josh%40gfunk007.com>
> >
>
>
--
"Therefore, send not to know For whom the bell tolls. It tolls for thee."
:: Josh 'G-Funk' McDonald
:: 0437 221 380 :: [EMAIL PROTECTED]
