commons/src/main/java/org/apache/tapestry5/ioc/OrderedConfiguration.java

// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
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//
// http://www.apache.org/licenses/LICENSE-2.0
//
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// distributed under the License is distributed on an "AS IS" BASIS,
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package org.apache.tapestry5.ioc;

/**
 * Object passed into a service contributor method that allows the method provide contributed values to the service's
 * configuration.
 *
 * A service can <em>collect</em> contributions in three different ways:
 * <ul>
 * <li>As an un-ordered collection of values</li>
 * <li>As an ordered list of values (where each value has a unique id, pre-requisites and post-requisites)</li>
 * <li>As a map of keys and values
 * </ul>
 *
 * The service defines the <em>type</em> of contribution, in terms of a base class or service interface. Contributions
 * must be compatible with the type, or be {@linkplain org.apache.tapestry5.ioc.services.TypeCoercer coercable} to the type.
 *
 * @see org.apache.tapestry5.ioc.annotations.Contribute
 * @see org.apache.tapestry5.ioc.annotations.UsesConfiguration
 */
public interface OrderedConfiguration<T>
{
    /**
     * Adds an ordered object to a service's contribution. Each object has an id (which must be unique). Optionally,
     * pre-requisites (a list of ids that must precede this object) and post-requisites (ids that must follow) can be
     * provided.
     *
     * If no constraints are supplied, then an implicit constraint is supplied: after the previously
     * contributed id <em>within the same contribution method</em>.
     *
     * @param id          a unique id for the object; the id will be fully qualified with the contributing module's id
     * @param constraints used to order the object relative to other contributed objects
     * @param object      to add to the service's configuration
     */
    void add(String id, T object, String... constraints);

    /**
     * Overrides a normally contributed object. Each override must match a single normally contributed object.
     *
     * @param id          identifies object to override
     * @param object      overriding object (may be null)
     * @param constraints constraints for the overridden object, replacing constraints for the original object (even if
     *                    omitted, in which case the override object will have no ordering constraints)
     * @since 5.1.0.0
     */
    void override(String id, T object, String... constraints);

    /**
     * Adds an ordered object by instantiating (with dependencies) the indicated class. When the configuration type is
     * an interface and the class to be contributed is a local file,
     * then a reloadable proxy for the class will be created and contributed.
     *
     * @param id          of contribution (used for ordering)
     * @param clazz       class to instantiate
     * @param constraints used to order the object relative to other contributed objects
     * @since 5.1.0.0
     */
    void addInstance(String id, Class<? extends T> clazz, String... constraints);

    /**
     * Instantiates an object and adds it as an override. When the configuration type is an interface and the class to
     * be contributed is a local file, then a reloadable proxy for the class will be created and contributed.
     *
     * @param id          of object to override
     * @param clazz       to instantiate
     * @param constraints constraints for the overridden object, replacing constraints for the original object (even if
     *                    omitted, in which case the override object will have no ordering constraints)
     * @since 5.1.0.0
     */
    void overrideInstance(String id, Class<? extends T> clazz, String... constraints);
}