    001// Licensed under the Apache License, Version 2.0 (the "License");
    002// you may not use this file except in compliance with the License.
    003// You may obtain a copy of the License at
    004//
    005// http://www.apache.org/licenses/LICENSE-2.0
    006//
    007// Unless required by applicable law or agreed to in writing, software
    008// distributed under the License is distributed on an "AS IS" BASIS,
    009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    010// See the License for the specific language governing permissions and
    011// limitations under the License.
    012
    013package org.apache.tapestry5.commons;
    014
    015/**
    016 * Object passed into a service contributor method that allows the method provide contributed values to the service's
    017 * configuration.
    018 *
    019 * A service can <em>collect</em> contributions in three different ways:
    020 * <ul>
    021 * <li>As an un-ordered collection of values</li>
    022 * <li>As an ordered list of values (where each value has a unique id, pre-requisites and post-requisites)</li>
    023 * <li>As a map of keys and values
    024 * </ul>
    025 *
    026 * The service defines the <em>type</em> of contribution, in terms of a base class or service interface. Contributions
    027 * must be compatible with the type, or be {@linkplain org.apache.tapestry5.commons.services.TypeCoercer coercable} to the type.
    028 *
    029 * @see org.apache.tapestry5.ioc.annotations.Contribute
    030 * @see org.apache.tapestry5.ioc.annotations.UsesConfiguration
    031 */
    032public interface OrderedConfiguration<T>
    033{
    034    /**
    035     * Adds an ordered object to a service's contribution. Each object has an id (which must be unique). Optionally,
    036     * pre-requisites (a list of ids that must precede this object) and post-requisites (ids that must follow) can be
    037     * provided.
    038     *
    039     * If no constraints are supplied, then an implicit constraint is supplied: after the previously
    040     * contributed id <em>within the same contribution method</em>.
    041     *
    042     * @param id          a unique id for the object; the id will be fully qualified with the contributing module's id
    043     * @param constraints used to order the object relative to other contributed objects
    044     * @param object      to add to the service's configuration
    045     */
    046    void add(String id, T object, String... constraints);
    047
    048    /**
    049     * Overrides a normally contributed object. Each override must match a single normally contributed object.
    050     *
    051     * @param id          identifies object to override
    052     * @param object      overriding object (may be null)
    053     * @param constraints constraints for the overridden object, replacing constraints for the original object (even if
    054     *                    omitted, in which case the override object will have no ordering constraints)
    055     * @since 5.1.0.0
    056     */
    057    void override(String id, T object, String... constraints);
    058
    059    /**
    060     * Adds an ordered object by instantiating (with dependencies) the indicated class. When the configuration type is
    061     * an interface and the class to be contributed is a local file,
    062     * then a reloadable proxy for the class will be created and contributed.
    063     *
    064     * @param id          of contribution (used for ordering)
    065     * @param clazz       class to instantiate
    066     * @param constraints used to order the object relative to other contributed objects
    067     * @since 5.1.0.0
    068     */
    069    void addInstance(String id, Class<? extends T> clazz, String... constraints);
    070
    071    /**
    072     * Instantiates an object and adds it as an override. When the configuration type is an interface and the class to
    073     * be contributed is a local file, then a reloadable proxy for the class will be created and contributed.
    074     *
    075     * @param id          of object to override
    076     * @param clazz       to instantiate
    077     * @param constraints constraints for the overridden object, replacing constraints for the original object (even if
    078     *                    omitted, in which case the override object will have no ordering constraints)
    079     * @since 5.1.0.0
    080     */
    081    void overrideInstance(String id, Class<? extends T> clazz, String... constraints);
    082}