Interface Callback

src/Callback.java:39–60

A simple 1-argument callback interface. Callbacks are typically created as anonymous classes. In order to make debugging easier, it is recommended to override the Object#toString method so that it returns a string that briefly explains what the callback does. If you use {@link Deferred

 * @param <T> The argument type of the callback.
 */
public interface Callback<R, T> {

  /**
   * The callback.
   * @param arg The argument to the callback.
   * @return The return value of the callback.
   * @throws Exception any exception.
   */
  public R call(T arg) throws Exception;

  /** The identity function (returns its argument).  */
  public static final Callback<Object, Object> PASSTHROUGH =
    new Callback<Object, Object>() {
      public Object call(final Object arg) {
        return arg;
      }
      public String toString() {
        return "passthrough";
      }
    };

}