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TypeOps xref
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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  package org.apache.giraph.types.ops;
19  
20  
21  /**
22   * Type operations, allowing working generically with mutable types,
23   * but still having efficient code.
24   * For example, by reducing object allocation via reuse.
25   *
26   * Use enum singleton pattern, having single enum value - INSTANCE.
27   * Serialization code depends on implementations being enums.
28   *
29   * @param <T> Type
30   */
31  public interface TypeOps<T> {
32    /**
33     * Class object for generic type T.
34     * @return Class&lt;T&gt; object
35     */
36    Class<T> getTypeClass();
37    /**
38     * Create new instance of type T.
39     * @return new instance
40     */
41    T create();
42    /**
43     * Create a copy of passed object
44     * @param from Object to copy
45     * @return Copy
46     */
47    T createCopy(T from);
48    /**
49     * Copies the value from the second argument into the first.
50     * @param to Object into which the value should be copied
51     * @param from Value of object to be copied
52     */
53    void set(T to, T from);
54  }