    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
    015package org.apache.tapestry5.ioc.annotations;
    016
    017import org.apache.tapestry5.ioc.def.ServiceDef;
    018
    019import java.lang.annotation.Documented;
    020import java.lang.annotation.Retention;
    021import java.lang.annotation.Target;
    022
    023import static java.lang.annotation.ElementType.METHOD;
    024import static java.lang.annotation.ElementType.TYPE;
    025import 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})
    044public @interface Marker
    045{
    046    /**
    047     * The type of annotation (which will be present at the injection point).
    048     */
    049    Class[] value();
    050}