PropertyHelper.PropertyEvaluator (Apache Ant API)
Date: 2016-04-09

org.apache.tools.ant

## Interface PropertyHelper.PropertyEvaluator

- All Superinterfaces:
    PropertyHelper.Delegate
  All Known Implementing Classes:
    LocalProperties
  Enclosing class:
    PropertyHelper

      public static interface PropertyHelper.PropertyEvaluator
      extends PropertyHelper.Delegate

  Looks up a property's value based on its name.

  Can be used to look up properties in a different storage than the project instance (like local properties for example) or to implement custom "protocols" like Ant's `${toString:refid}` syntax.

  Since:
    Ant 1.8.0

- - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `java.lang.Object` | `evaluate(java.lang.String property, PropertyHelper propertyHelper)` Evaluate a property.

- - ### Method Detail

    - #### evaluate

          java.lang.Object evaluate(java.lang.String property,
                                  PropertyHelper propertyHelper)

      Evaluate a property.
      Parameters:
        `property` - the property's String "identifier".
        `propertyHelper` - the invoking PropertyHelper.
      Returns:
        null if the property name could not be found, an instance of `NullReturn` to indicate a property with a name that can be matched but a value of `null` and the property's value otherwise.