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Berkeley DB Java Edition is a open source, transactional storage solution for Java applications. The Direct Persistence Layer (DPL) API is faster and easier to develop, deploy, and manage than serialized object files or ORM-based Java persistence solutions. The Collections API enhances the standard java.util.collections classes allowing them to be persisted to a local file system and accessed concurrently while protected by ACID transactions. Data is stored by serializing objects and managing class and instance data separately so as not to waste space. Berkeley DB Java Edition is the reliable drop-in solution for complex, fast, and scalable storage. Source for this release is in 'je-4.0.92-sources.jar', the Javadoc is located at 'http://download.oracle.com/berkeley-db/docs/je/4.0.92/'.

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/*-
 * Copyright (C) 2002, 2018, Oracle and/or its affiliates. All rights reserved.
 *
 * This file was distributed by Oracle as part of a version of Oracle Berkeley
 * DB Java Edition made available at:
 *
 * http://www.oracle.com/technetwork/database/database-technologies/berkeleydb/downloads/index.html
 *
 * Please see the LICENSE file included in the top-level directory of the
 * appropriate version of Oracle Berkeley DB Java Edition for a copy of the
 * license and additional information.
 */

package com.sleepycat.persist.evolve;

/**
 * A mutation for deleting an entity class or field.
 *
 * WARNING: The data for the deleted class or field will be
 * destroyed and will be recoverable only by restoring from backup.  If you
 * wish to convert the instance data to a different type or format, use a
 * {@link Conversion} mutation instead.
 *
 * For example, to delete a field:
 *
 *  *  package my.package;
 *
 *  // The old class.  Version 0 is implied.
 *  //
 *  {@literal @Entity}
 *  class Person {
 *      String name;
 *      String favoriteColors;
 *  }
 *
 *  // The new class.  A new version number must be assigned.
 *  //
 *  {@literal @Entity(version=1)}
 *  class Person {
 *      String name;
 *  }
 *
 *  // Add the mutation for deleting a field.
 *  //
 *  Mutations mutations = new Mutations();
 *
 *  mutations.addDeleter(new Deleter(Person.class.getName(), 0,
 *                                   "favoriteColors");
 *
 *  // Configure the mutations as described {@link Mutations here}.
 *
 * To delete an entity class:
 *
 *  *  package my.package;
 *
 *  // The old class.  Version 0 is implied.
 *  //
 *  {@literal @Entity}
 *  class Statistics {
 *      ...
 *  }
 *
 *  // Add the mutation for deleting a class.
 *  //
 *  Mutations mutations = new Mutations();
 *
 *  mutations.addDeleter(new Deleter("my.package.Statistics", 0));
 *
 *  // Configure the mutations as described {@link Mutations here}.
 *
 * @see com.sleepycat.persist.evolve Class Evolution
 * @author Mark Hayes
 */
public class Deleter extends Mutation {

    private static final long serialVersionUID = 446348511871654947L;

    /**
     * Creates a mutation for deleting an entity class.
     *
     * @param className the class to which this mutation applies.
     * @param classVersion the class version to which this mutation applies.
     */
    public Deleter(String className, int classVersion) {
        super(className, classVersion, null);
    }

    /**
     * Creates a mutation for deleting the given field from all instances of
     * the given class version.
     *
     * @param declaringClass the class to which this mutation applies.
     * @param declaringClassVersion the class version to which this mutation
     * applies.
     * @param fieldName field name to which this mutation applies.
     */
    public Deleter(String declaringClass, int declaringClassVersion,
                   String fieldName) {
        super(declaringClass, declaringClassVersion, fieldName);
    }

    @Override
    public String toString() {
        return "[Deleter " + super.toString() + ']';
    }
}