Package ai.timefold.solver.core.api.domain.variable

Annotation Interface CascadingUpdateShadowVariable

@Target(FIELD) @Retention(RUNTIME) public @interface CascadingUpdateShadowVariable
Specifies that a field may be updated by the target method when any of its variables change, genuine or shadow.

Automatically cascades change events to the subsequent elements of a PlanningListVariable.

A single listener is created to execute user-defined logic from the targetMethod after all variable changes have been applied. This means it will be the last step executed during the event lifecycle.

It can be applied in multiple fields to update various shadow variables. The user's logic is responsible for defining the order in which each variable is updated.

Distinct targetMethod can be defined, but there is no guarantee about the order in which they are executed. Therefore, caution is required when using multiple targetMethod per model.

Except for PiggybackShadowVariable, the use of CascadingUpdateShadowVariable as a source for other variables, such as ShadowVariable, is not allowed.

Important: it must only change the shadow variable(s) for which it's configured. It should never change a genuine variable or a problem fact. It can change its shadow variable(s) on multiple entity instances (for example: an arrivalTime change affects all trailing entities too).

  • Required Element Summary

    Required Elements
    Modifier and Type
    Required Element
    Description
    String
    targetMethodName
    The target method element.

  • Element Details

    • targetMethodName

      String targetMethodName
      The target method element.

      Important: the method must be non-static and should not include any parameters. There are no restrictions regarding the method visibility. There is no restriction on the method's return type, but if it returns a value, it will be ignored and will not impact the listener's execution.

      Returns:
      method name of the source host element which will update the shadow variable