001    // Copyright 2006, 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 java.lang.annotation.Documented;
018    import static java.lang.annotation.ElementType.FIELD;
019    import java.lang.annotation.Retention;
020    import static java.lang.annotation.RetentionPolicy.RUNTIME;
021    import java.lang.annotation.Target;
022    
023    import static org.apache.tapestry5.ioc.annotations.AnnotationUseContext.COMPONENT;
024    import org.apache.tapestry5.ioc.annotations.UseWith;
025    
026    /**
027     * Defines an <em>implementation</em> mixin for a component.
028     */
029    @Target(FIELD)
030    @Documented
031    @Retention(RUNTIME)
032    @UseWith({COMPONENT})
033    public @interface Mixin
034    {
035    
036        /**
037         * Defines the type of mixin, using a logical mixin name. This value takes precedence over the type of field (to
038         * which the annotation is attached). In such cases, it is presumed that the field's type is an interface
039         * implemented by the actual mixin. The default value (the empty string) directs Tapestry to use the field type as
040         * the mixin class to instantiate and attach to the component.
041         */
042        String value() default "";
043    
044        /**
045         * Defines an ordering constraint for when the mixin should be applied in relation to other mixins.
046         * The string is analagous exactly to the strings used to define ordered contributions.
047         * Eg: @Mixin(order={"before:mixina","after:mixinb"}). The ids are mixin names and are case insensitive.
048         * @since 5.2.0.0
049         */
050        String[] order() default {};
051    }