Value changes upon instance replacement

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Erik's note: this is part of a larger "improved UI events" feature.

Original post from ErikBruchez:


Date: Fri, 18 May 2007 17:16:25 +0200
To: public-forms@w3.org
Subject: Value changes upon instance replacement
From: "Erik Bruchez" <ebruchez@orbeon.com>
Cc: www-forms-editor@w3.org

All,

At the moment, I don't think this is clearly specified to happen.

Use case:

1. <xforms:input ref="name">

2. The instance containing "name" is replaced.

3. Section 11.2 specifies that a refresh must take place. However, no
     node of the new instance is marked as having changed as I
     understand it. 4.3.4 says "If the value of an instance data node
     was changed, then the node must be marked for dispatching the
     xforms-value-changed event.". But in this case, the value of the
     node hasn't changed because the node is just freshly created from
     the instance replacement.

4. Consequence: no xforms-value-changed is fired.

This behavior is very non-intuitive because you can replace an
instance under controls' feet and while the control may update their
values in the UI, no xforms-value-changed is fired.

This means that you cannot reliably use events to determine if the
value of a control has changed or not. I think that this should be
possible, or the usefulness of value-changed-events is greatly
reduced.

-Erik