Property-Seek-Value method
Use this method to initiate backward chaining computations for the value of a property, based on Declare Expression rules.
Parameters
This method has four parameters:
| Parameter | Description |
|---|---|
| GoalProperty | Identify the property to compute. This must be the Target Property key part of a Declare Expression rule. |
| AlwaysRecompute |
Select to force the system to compute the value of the property identified in
the
GoalProperty
parameter even when the property already is
present on the clipboard and has a non-null value.
In most cases, leave this box cleared, so that the Compute Value field in the Declare Expression rule applies. |
| AlwaysForwardChain |
Select to cause the system to forward chain after backward chaining, even when
the goal-seek attempt failed. If not selected, when goal seeking fails, any property
changes made by the goal seek process are not considered for forward chaining.
In most cases, leave this box cleared. |
| MissingReference Property | Optional. Enter a target property, a local variable, or an activity parameter. When backward chaining fails to compute the property identified in the GoalProperty parameter, the method stores name of the property that prevented the computation from completing there. |
Results
This method uses backward chaining on the declarative networ k defined through Declare Expression rules to compute or recompute the value of the goal property.
The system uses the GoalProperty parameter and class of the step page (or primary page) as the Applies To key part to search for the Declare Expression rule. It then uses the Declare Expression rule to starts backward-chaining computations to obtain a value for the property.
If backward chaining is successful, the result is a new value for the property identified in the GoalProperty parameter. (Other properties may also have new values, all consistent with Declare Expression rules and other declarative rules).
If the backward chaining computation is unable to compute a value for the GoalProperty property, it may return instead the name of another property (identified in the third parameter) that — if it had a value — could contribute to the computation. Your application may then prompt a user for a value for this property, or use other means to obtain this value.