    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}