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Arez Annotations

There is a newer version: 0.95

package arez.annotations;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Target;
import javax.annotation.Nonnull;

/**
 * Methods marked with this annotation are dependencies of the component.
 * THe component observes the dependency and if the dependency is disposed takes
 * an action to cascade the dispose or null the property referencing dependency.
 *
 * The method that is annotated with @Dependency must comply with the additional constraints:
 * 
 * Must not be annotated with any other arez annotation except {@link Observable} or {@link Computed}
 * Must have 0 parameters
 * Must return a value
 * Must not be private
 * Must not be static
 * Must not be abstract
 * Must not throw exceptions
 * 
 */
@Documented
@Target( ElementType.METHOD )
public @interface Dependency
{
  /**
   * The action to take when dependency is disposed.
   */
  enum Action
  {
    /**
     * Remove the component.
     */
    CASCADE,
    /**
     * Set the {@link Observable} property that holds dependency to null.
     */
    SET_NULL
  }

  /**
   * Return the action to take when the dependency is disposed.
   * A {@link Action#CASCADE} value indicates that the component should be deleted, while a
   * {@link Action#SET_NULL} value indicates that the observable field should be set to null.
   * The {@link Action#SET_NULL} is only valid on {@link Observable} properties that have an
   * associated setter and are not annotated with {@link javax.annotation.Nonnull}.
   *
   * @return the action to take when the dependency is disposed.
   */
  @Nonnull
  Action action() default Action.CASCADE;
}