@initial MIP text, take 1

The initial Property

This property is evaluated during model initialization, to calculate an 
initial value for a node. It overwrites any existing value the node may 
have.

Computed Expression: Yes.
Legal Values: Any expression.
Default Value: none.
Inheritance Rules: does not inherit.

The expression is evaluated and if it succeeds the result is converted to 
string and stored as the value content of the associated data node. If the 
evaluation fails, the value content is set to the empty sequence.

Example

<bind ref="today" initial="now()"/>

[Question: presumably not allowed on controls, as with @calculate]
[Question: presumably happens during model construct, just before the first 
update]
[Question: if there are no instance elements, the data model is not 
constructed until after the first update, during UI initialization; does 
@initial still apply?]
[Something will have to be added to Model Initialization] 
[Erik's @default also happens on <insert/>; do we want that?]

Received on Friday, 31 May 2024 09:29:19 UTC