001    // Copyright 2010, 2011 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    // http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5.ioc.internal;
016    
017    import org.apache.tapestry5.ioc.ObjectLocator;
018    import org.apache.tapestry5.ioc.internal.util.InternalUtils;
019    
020    public abstract class AbstractConfigurationImpl<T>
021    {
022        private final Class<T> contributionType;
023    
024        private final ObjectLocator locator;
025    
026        public AbstractConfigurationImpl(Class<T> contributionType, ObjectLocator locator)
027        {
028            this.contributionType = contributionType;
029            this.locator = locator;
030        }
031    
032        protected T instantiate(Class<? extends T> clazz)
033        {
034            assert clazz != null;
035    
036            // Only attempt to proxy the class if it is the right type for the contribution. Starting
037            // in 5.3, it is allowed to make contributions of different types (as long as they can be
038            // coerced to the right type) ... but this means that sometimes, a class is passed that isn't
039            // assignable to the actual contribution type.
040    
041            if (contributionType.isInterface() && InternalUtils.isLocalFile(clazz)
042                    && contributionType.isAssignableFrom(clazz))
043                return locator.proxy(contributionType, clazz);
044    
045            return locator.autobuild(clazz);
046        }
047    }