    001    // Copyright 2007, 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 org.apache.tapestry5.ioc.def.ServiceDef;
    018
    019    import java.lang.annotation.Documented;
    020    import java.lang.annotation.Retention;
    021    import java.lang.annotation.Target;
    022
    023    import static java.lang.annotation.ElementType.METHOD;
    024    import static java.lang.annotation.ElementType.TYPE;
    025    import static java.lang.annotation.RetentionPolicy.RUNTIME;
    026
    027    /**
    028     * Used to define one or more {@linkplain ServiceDef#getMarkers() marker annotations} for a service implementation. This
    029     * allows for injection based on the combination of type and marker interface. These marker interfaces should not have
    030     * any values. The mere presence of the marker annotation is all that is needed.
    031     * <p/>
    032     * When applied to a module class, this sets the default markers for all services within the module.  Markers are
    033     * additive, so a Marker annotation on the implementation class and/or specified with {@link
    034     * org.apache.tapestry5.ioc.ServiceBindingOptions#withMarker(Class[])} will accumulate; a service may have any number of
    035     * markers.  Generally one or two is enough.
    036     *
    037     * @see org.apache.tapestry5.ioc.ObjectLocator#getService(Class, Class[])
    038     */
    039    @Target(
    040            {TYPE, METHOD})
    041    @Retention(RUNTIME)
    042    @Documented
    043    @UseWith({AnnotationUseContext.SERVICE, AnnotationUseContext.MODULE})
    044    public @interface Marker
    045    {
    046        /**
    047         * The type of annotation (which will be present at the injection point).
    048         */
    049        Class[] value();
    050    }