001/*
002 *  Licensed to the Apache Software Foundation (ASF) under one
003 *  or more contributor license agreements.  See the NOTICE file
004 *  distributed with this work for additional information
005 *  regarding copyright ownership.  The ASF licenses this file
006 *  to you under the Apache License, Version 2.0 (the
007 *  "License"); you may not use this file except in compliance
008 *  with the License.  You may obtain a copy of the License at
009 *
010 *        http://www.apache.org/licenses/LICENSE-2.0
011 *
012 *  Unless required by applicable law or agreed to in writing,
013 *  software distributed under the License is distributed on an
014 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 *  KIND, either express or implied.  See the License for the
016 *  specific language governing permissions and limitations
017 *  under the License.
018 */
019
020package org.apache.isis.core.metamodel.spec;
021
022import org.apache.isis.core.metamodel.adapter.ObjectAdapter;
023
024public abstract class InstanceAbstract implements Instance {
025
026    private Specification specification;
027
028    protected InstanceAbstract() {
029        this(null, null);
030    }
031
032    protected InstanceAbstract(final ObjectAdapter owner) {
033        this(owner, null);
034    }
035
036    protected InstanceAbstract(final ObjectAdapter owner, final Specification specification) {
037        this.specification = specification;
038    }
039
040    @Override
041    public Specification getSpecification() {
042        if (specification == null) {
043            specification = loadSpecification();
044        }
045        return specification;
046    }
047
048    /**
049     * Allows the specification to be lazily loaded.
050     */
051    protected Specification loadSpecification() {
052        return null;
053    }
054
055    /**
056     * Allows subclasses to get specification without necessarily triggering
057     * {@link #loadSpecification() loading} if not yet known.
058     */
059    protected final Specification getSpecificationNoLoad() {
060        return specification;
061    }
062
063}