/*
 * This file is part of ELKI:
 * Environment for Developing KDD-Applications Supported by Index-Structures
 *
 * Copyright (C) 2022
 * ELKI Development Team
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package elki.database.ids;

/**
 * Database ID object.
 * <p>
 * While this currently is just an Integer, it should be avoided to store the
 * object IDs in regular integers to reduce problems if this API ever changes
 * (for example if someone needs to do context tracking for debug purposes!)
 * <p>
 * In particular, a developer should not make any assumption of these IDs being
 * consistent across multiple results/databases.
 *
 * @author Erich Schubert
 * @since 0.4.0
 *
 * @opt nodefillcolor LemonChiffon
 */
public interface DBID extends DBIDRef, Comparable<DBIDRef>, ArrayDBIDs, SetDBIDs {
  /**
   * In contrast to {@link DBIDRef}, the DBID interface is supposed to have a
   * stable hash code. However, it is generally preferred to use optimized
   * storage classes instead of Java collections!
   *
   * @return hash code
   */
  @Override
  int hashCode();

  /**
   * In contrast to {@link DBIDRef}, the DBID interface is supposed to have a
   * stable equals for other DBIDs.
   * <p>
   * Yet, {@link DBIDUtil#equal} is more type safe and explicit.
   *
   * @param obj Other object
   * @return true when the object is the same DBID.
   */
  @Override
  @Deprecated
  boolean equals(Object obj);

  /**
   * Compare two DBIDs for ordering.
   * <p>
   * Consider using {@link DBIDUtil#compare}, which is more explicit.
   *
   * @param other Other DBID object
   * @return Comparison result
   */
  @Override
  int compareTo(DBIDRef other);
}
