Deleter


1   /*-
2    * See the file LICENSE for redistribution information.
3    *
4    * Copyright (c) 2002,2006 Oracle.  All rights reserved.
5    *
6    * $Id: Deleter.java,v 1.7 2006/10/30 21:14:31 bostic Exp $
7    */
8   
9   package com.sleepycat.persist.evolve;
10  
11  /**
12   * A mutation for deleting an entity class or field.
13   *
14   * <p><strong>WARNING:</strong> The data for the deleted class or field will be
15   * destroyed and will be recoverable only by restoring from backup.  If you
16   * wish to convert the instance data to a different type or format, use a
17   * {@link Conversion} mutation instead.</p>
18   *
19   * <p>For example, to delete a field:</p>
20   *
21   * <pre class="code">
22   *  package my.package;
23   *
24   *  // The old class.  Version 0 is implied.
25   *  //
26   *  {@literal @Entity}
27   *  class Person {
28   *      String name;
29   *      String favoriteColors;
30   *  }
31   *
32   *  // The new class.  A new version number must be assigned.
33   *  //
34   *  {@literal @Entity(version=1)}
35   *  class Person {
36   *      String name;
37   *  }
38   *
39   *  // Add the mutation for deleting a field.
40   *  //
41   *  Mutations mutations = new Mutations();
42   *
43   *  mutations.addDeleter(new Deleter(Person.class.getName(), 0,
44   *                                   "favoriteColors");
45   *
46   *  // Configure the mutations as described {@link Mutations here}.</pre>
47   *
48   * <p>To delete an entity class:</p>
49   *
50   * <pre class="code">
51   *  package my.package;
52   *
53   *  // The old class.  Version 0 is implied.
54   *  //
55   *  {@literal @Entity}
56   *  class Statistics {
57   *      ...
58   *  }
59   *
60   *  // Add the mutation for deleting a class.
61   *  //
62   *  Mutations mutations = new Mutations();
63   *
64   *  mutations.addDeleter(new Deleter("my.package.Statistics", 0));
65   *
66   *  // Configure the mutations as described {@link Mutations here}.</pre>
67   *
68   * @see com.sleepycat.persist.evolve Class Evolution
69   * @author Mark Hayes
70   */
71  public class Deleter extends Mutation {
72  
73      private static final long serialVersionUID = 446348511871654947L;
74  
75      /**
76       * Creates a mutation for deleting an entity class.
77       */
78      public Deleter(String   className, int classVersion) {
79          super(className, classVersion, null);
80      }
81  
82      /**
83       * Creates a mutation for deleting the given field from all instances of
84       * the given class version.
85       */
86      public Deleter(String   declaringClass, int declaringClassVersion,
87                     String   fieldName) {
88          super(declaringClass, declaringClassVersion, fieldName);
89      }
90  
91      @Override  
92      public String   toString() {
93          return "[Deleter " + super.toString() + ']';
94      }
95  }
96
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