001/* -*- mode: Java; c-basic-offset: 2; indent-tabs-mode: nil; coding: utf-8-unix -*-
002 *
003 * Copyright © 2024 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.bean;
015
016import java.util.Objects;
017
018/**
019 * An assignment of a contextual reference to an {@link AttributedElement}, usually as {@linkplain
020 * Request#reference(BeanSelectionCriteria) completed by} a {@link Request}.
021 *
022 * @param <R> the type of contextual reference
023 *
024 * @param assignee the {@link AttributedElement}; must not be {@code null}
025 *
026 * @param value the contextual reference; may be {@code null}
027 *
028 * @author <a href="https://about.me/lairdnelson" target="_top">Laird Nelson</a>
029 */
030// You're going to be tempted to replace the value component with a Supplier component. Don't do it. An assignment is a
031// value that belongs to, e.g., a field, so even if the value "came from" none/dependent/prototype scope, it was already
032// sourced and "belongs to" the field.
033public record Assignment<R>(AttributedElement assignee, R value) {
034
035  /**
036   * Creates a new {@link Assignment}.
037   *
038   * @param assignee the {@link AttributedElement}; must not be {@code null}
039   *
040   * @param value the contextual reference; may be {@code null}
041   */
042  public Assignment {
043    Objects.requireNonNull(assignee, "assignee");
044  }
045
046}