api/applib/src/main/java/org/apache/causeway/applib/spec/Specification.java

/*
 *  Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *        http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
 */
package org.apache.causeway.applib.spec;

import org.apache.causeway.applib.annotation.Programmatic;

/**
 * An implementation of the <i>Specification</i> pattern, as described in Eric
 * Evans' <i>Domain Driven Design</i>, p224.
 *
 * @since 1.x {@index}
 */
public interface Specification {

    /**
     * If <tt>null</tt> then satisfied, otherwise is reason why the
     * specification is not satisfied.
     */
    @Programmatic
    String satisfies(Object obj);

}