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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 ComputedValues within Arez.
 *
 * The return value should be derived from other Observables within the Arez system
 * and the value returned by the method should not change unless the state of the other
 * {@link Observable}s change. The method is wrapped in a READ_ONLY transaction and
 * thus can not modify other state in the system.
 *
 * The method that is annotated with @Computed must comply with the additional constraints:
 * 
 * Must not be annotated with any other arez annotation
 * Must have 0 parameters
 * Must return a value
 * Must not be private
 * Must not be static
 * Must not be final
 * Must not be abstract
 * Must not throw exceptions
 * 
 */
@Documented
@Target( ElementType.METHOD )
public @interface Computed
{
  /**
   * Return the name of the ComputedValue relative to the component.
   * The value must conform to the requirements of a java identifier.
   * The name must also be unique across {@link Observable}s,
   * {@link Computed}s and {@link Action}s within the scope of the
   * {@link ArezComponent} annotated element.
   *
   * @return the name of the ComputedValue relative to the component.
   */
  @Nonnull
  String name() default "";
}