01: /*
02: * Copyright 2002-2006 the original author or authors.
03: *
04: * Licensed under the Apache License, Version 2.0 (the "License");
05: * you may not use this file except in compliance with the License.
06: * You may obtain a copy of the License at
07: *
08: * http://www.apache.org/licenses/LICENSE-2.0
09: *
10: * Unless required by applicable law or agreed to in writing, software
11: * distributed under the License is distributed on an "AS IS" BASIS,
12: * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13: * See the License for the specific language governing permissions and
14: * limitations under the License.
15: */
16:
17: package org.springframework.beans;
18:
19: /**
20: * Interface representing an object whose value set can be merged with
21: * that of a parent object.
22: *
23: * @author Rob Harrop
24: * @since 2.0
25: * @see org.springframework.beans.factory.support.ManagedSet
26: * @see org.springframework.beans.factory.support.ManagedList
27: * @see org.springframework.beans.factory.support.ManagedMap
28: * @see org.springframework.beans.factory.support.ManagedProperties
29: */
30: public interface Mergeable {
31:
32: /**
33: * Is merging enabled for this particular instance?
34: */
35: boolean isMergeEnabled();
36:
37: /**
38: * Merge the current value set with that of the supplied object.
39: * <p>The supplied object is considered the parent, and values in
40: * the callee's value set must override those of the supplied object.
41: * @param parent the object to merge with
42: * @return the result of the merge operation
43: * @throws IllegalArgumentException if the supplied parent is <code>null</code>
44: * @exception IllegalStateException if merging is not enabled for this instance
45: * (i.e. <code>mergeEnabled</code> equals <code>false</code>).
46: */
47: Object merge(Object parent);
48:
49: }
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