001/* -*- mode: Java; c-basic-offset: 2; indent-tabs-mode: nil; coding: utf-8-unix -*-
002 *
003 * Copyright © 2023–2025 microBean™.
004 *
005 * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
006 * the License. You may obtain a copy of the License at
007 *
008 *     http://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
011 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
012 * specific language governing permissions and limitations under the License.
013 */
014package org.microbean.reference;
015
016import java.util.function.Supplier;
017
018import org.microbean.bean.Id;
019
020import org.microbean.proxy.Proxy;
021
022/**
023 * A source of {@link Proxy} instances representing <dfn>client proxies</dfn>.
024 *
025 * @author <a href="https://about.me/lairdnelson" target="_top">Laird Nelson</a>
026 *
027 * @see #clientProxy(Id, Supplier)
028 */
029@FunctionalInterface
030public interface ClientProxier {
031
032  /**
033   * Returns a <dfn>contextual reference</dfn> which is also a {@link Proxy}, given a {@link Supplier} of
034   * <dfn>contextual instances</dfn> of the appropriate type.
035   *
036   * <p>Implementations of this method may return {@code null}.</p>
037   *
038   * @param <R> the type of the contextual reference
039   *
040   * @param id an {@link Id} qualifying the contextual instance that will be proxied; must not be {@code null}
041   *
042   * @param instanceSupplier a {@link Supplier} of contextual instances of the appropriate type; must not be {@code null}
043   *
044   * @return a contextual reference, which may be {@code null}
045   *
046   * @exception NullPointerException if any argument is {@code null}
047   *
048   * @see Proxy
049   */
050  public <R> R clientProxy(final Id id, final Supplier<? extends R> instanceSupplier);
051
052}