001    // Copyright 2007, 2008, 2009, 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.annotations;
016    
017    import java.lang.annotation.Documented;
018    import java.lang.annotation.Retention;
019    import java.lang.annotation.Target;
020    
021    import static java.lang.annotation.ElementType.FIELD;
022    import static java.lang.annotation.ElementType.PARAMETER;
023    import static java.lang.annotation.RetentionPolicy.RUNTIME;
024    import static org.apache.tapestry5.ioc.annotations.AnnotationUseContext.*;
025    
026    /**
027     * Used to inject a symbol value, via a symbol name. This is used much like {@link
028     * org.apache.tapestry5.ioc.annotations.Value} annotation, except that symbols are not expanded ... the entire value is
029     * a symbol name. This allows the annotation to reference a public constant variable.
030     * <p/>
031     * <p/>
032     * The injected value may be coerced from string to an alternate type (defined by the field or parameter to which
033     * the @Symbol annotation is attached). For better control, use the {@link IntermediateType} annotation as well, which
034     * allows the string to be coerced to an alternate type before being coerced a second time to the field or parameter type.
035     */
036    @Target(
037            {PARAMETER, FIELD})
038    @Retention(RUNTIME)
039    @Documented
040    @UseWith({COMPONENT, MIXIN, PAGE, SERVICE})
041    public @interface Symbol
042    {
043        /**
044         * The name of the symbol to inject.
045         */
046        String value();
047    }