001    // Copyright 2007, 2009 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.annotations;
016    
017    import org.apache.tapestry5.Block;
018    import org.apache.tapestry5.ioc.annotations.Inject;
019    import org.apache.tapestry5.ioc.annotations.UseWith;
020    import static org.apache.tapestry5.ioc.annotations.AnnotationUseContext.*;
021    
022    import java.lang.annotation.Documented;
023    import static java.lang.annotation.ElementType.FIELD;
024    import java.lang.annotation.Retention;
025    import static java.lang.annotation.RetentionPolicy.RUNTIME;
026    import java.lang.annotation.Target;
027    
028    /**
029     * Optional annotation, used with {@link Inject}, which exists to provide the id of an object when it can not be
030     * determined by other means (such as from the field name). Currently, this is used when injecting a {@link Block}.
031     */
032    @Target(FIELD)
033    @Documented
034    @Retention(RUNTIME)
035    @UseWith({COMPONENT,MIXIN,PAGE,SERVICE})
036    public @interface Id
037    {
038        /**
039         * The id.
040         */
041        String value();
042    }