I can see some validity to that argument. On the other hand, since Pivot has
another means of data binding that is better suited to the use case you
describe, I think it makes sense to leave the namespace binding feature as-is
and see how it ends up being used. What you describe could easily be added in a
future update.
On Jul 19, 2010, at 9:26 AM, Michael Allman wrote:
> On Mon, 19 Jul 2010, Greg Brown wrote:
>
>>>>> What about properties of properties of objects---like
>>>>> ${obj.prop.subprop}? If the "obj.prop" value changes, do the binding
>>>>> listeners get notified?
>>>>
>>>> No, because those listeners have indicated that the property they care
>>>> about is "subprop". They don't necessarily know or care that "prop" is
>>>> referred to by another object ("obj", in this case).
>>>
>>> I can't think of a case off the top of my head where you would actually run
>>> into this situation in the current implementation. If you can, it would
>>> help illustrate the problem.
>>
>> I think the current implementation is valid. But just for comparison, it
>> would be useful to know what Flex does in this case.
>
> You have the flex-ibility (sorry, couldn't help myself) to define a "site"
> and a "chain" when creating bindings in code. The "site" is the root of the
> bound hierarchy. The "chain" is the sequence of properties for each of which
> a listener is registered. If any property in the chain changes, the bound
> listener will receive a notification if the last property in the chain does
> in fact change.
>
> But bindings are rarely done in code and are rarely thought out that
> thoroughly. By default, in a root-property sequence
> "object.prop1.prop2.prop3..." any change in any of prop1, prop2, prop3, etc.
> will notify a listener. I think I can give a simple example of why this is
> desirable.
>
> Suppose a component binds one of its properties to the expression
> "person.name.first". If first changes from "John" to "Jane" the listener
> will receive a notification of a change in "person.name.first" from "John" to
> "Jane". If name changes from {first: "John", last: "Doe"} to {first: "Jane",
> last: "Doe"}, shouldn't the listener know the first name changed? Strictly
> speaking, the original name's "first" property didn't change---it's still
> "John".
>
> Similarly, if person is reassigned from person1 to person2 and they have
> different first names, etc. If this person is a data model backing a form,
> and the person is changed wholesale, any "first name"
> labels/inputs/validators/parsers/what-have-you need to know.
>
> Cheers,
>
> Michael
