001// Copyright 2006, 2008, 2009, 2010, 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;
016
017/**
018 * Object passed into a service contributor method that allows the method provide contributed values to the service's
019 * configuration.
020 * <p/>
021 * A service can <em>collect</em> contributions in three different ways:
022 * <ul>
023 * <li>As an un-ordered collection of values</li>
024 * <li>As an ordered list of values (where each value has a unique id, pre-requisites and post-requisites)</li>
025 * <li>As a map of keys and values
026 * </ul>
027 * <p/>
028 * The service defines the <em>type</em> of contribution, in terms of a base class or service interface. Contributions
029 * must be compatible with the type, or be {@linkplain org.apache.tapestry5.ioc.services.TypeCoercer coercable} to the type.
030 *
031 * @see org.apache.tapestry5.ioc.annotations.Contribute
032 * @see org.apache.tapestry5.ioc.annotations.UsesConfiguration
033 */
034public interface OrderedConfiguration<T>
035{
036    /**
037     * Adds an ordered object to a service's contribution. Each object has an id (which must be unique). Optionally,
038     * pre-requisites (a list of ids that must precede this object) and post-requisites (ids that must follow) can be
039     * provided.
040     * <p/>
041     * <p>If no constraints are supplied, then an implicit constraint is supplied: after the previously
042     * contributed id <em>within the same contribution method</em>.
043     *
044     * @param id          a unique id for the object; the id will be fully qualified with the contributing module's id
045     * @param constraints used to order the object relative to other contributed objects
046     * @param object      to add to the service's configuration
047     */
048    void add(String id, T object, String... constraints);
049
050    /**
051     * Overrides a normally contributed object. Each override must match a single normally contributed object.
052     *
053     * @param id          identifies object to override
054     * @param object      overriding object (may be null)
055     * @param constraints constraints for the overridden object, replacing constraints for the original object (even if
056     *                    omitted, in which case the override object will have no ordering constraints)
057     * @since 5.1.0.0
058     */
059    void override(String id, T object, String... constraints);
060
061    /**
062     * Adds an ordered object by instantiating (with dependencies) the indicated class. When the configuration type is
063     * an interface and the class to be contributed is a local file,
064     * then a reloadable proxy for the class will be created and contributed.
065     *
066     * @param id          of contribution (used for ordering)
067     * @param clazz       class to instantiate
068     * @param constraints used to order the object relative to other contributed objects
069     * @since 5.1.0.0
070     */
071    void addInstance(String id, Class<? extends T> clazz, String... constraints);
072
073    /**
074     * Instantiates an object and adds it as an override. When the configuration type is an interface and the class to
075     * be contributed is a local file, then a reloadable proxy for the class will be created and contributed.
076     *
077     * @param id          of object to override
078     * @param clazz       to instantiate
079     * @param constraints constraints for the overridden object, replacing constraints for the original object (even if
080     *                    omitted, in which case the override object will have no ordering constraints)
081     * @since 5.1.0.0
082     */
083    void overrideInstance(String id, Class<? extends T> clazz, String... constraints);
084}