[jsr-314-open-mirror] [jsr-314-open] [2.1 Spec Review] Transient State [Was: Fix UIData state saving model]

[Andy Schwartz]

Hey Martin -

Here is how I was thinking about this...

With transient properties, we have two types of use cases:

1.  Components storing transient attributes on themselves.
2.  External classes storing transient attributes on components.

The use case you mention below falls under #1.

In earlier threads there were a references to use cases that fall under 
#2 (eg. a renderer setting a transient property on a component).

If we go with the original API proposal of adding public methods to 
UIComponent, ie:

- public Object getTransient(Object key)
- public Object putTransient(Object key, Object value)

We have everything we need to address #1 and #2.  Your sample below can 
be rewritten as:

Double getCalculatedWeight() {
  return (Double) getTransient(PropertyKeys.weight, false);
}
void setCalculatedWeight(Double weight) {
  putTransient(PropertyKeys.weight, weight);
}

I don't see how adding a new TransientStateHelper contract improves this 
situation.  That's not to say that we cannot do this.  The first patch 
that I provided leaves TransientStateHelper in place.  Just seems like 
added conceptual overhead that might not be necessary.

Andy


On 10/22/10 7:02 AM, Martin Marinschek wrote:
> Hi Andy,
>
> maybe I am missing something here, but isn't the normal use-case for
> this a new component which adds a transient attribute?
>
> something like: calculatedWeight. This should of course be exposed via
> the API of the component - so there should be a:
>
> Double getCalculatedWeight();
> void setCalculatedWeight(Double weight);
>
> And my point was that the implementation of these stateless getters
> and setters should look similar to the stateful version.
>
> What I would do:
>
> Double getCalculatedWeight() {
>   return (Double) getTransientStateHelper().get(PropertyKeys.weight, false);
> }
> void setCalculatedWeight(Double weight) {
>   getTransientStateHelper().put(PropertyKeys.weight, weight);
> }
>
> Could TransientStateHelper not be an alternative implementation of the
> StateHelper interface?
>
> best regards,
>
> Martin
>
>