001    // Copyright 2008 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5.corelib.data;
016    
017    /**
018     * Used with the {@link org.apache.tapestry5.corelib.components.Select} component to control whether an initial blank
019     * option is supplied.  Determines the optionality of the undelrying property from the Select's {@linkplain
020     * org.apache.tapestry5.FieldValidator#isRequired() validate parameter}
021     */
022    public enum BlankOption
023    {
024        /**
025         * Always include the blank option, even if the underlying property is required.
026         */
027        ALWAYS,
028    
029        /**
030         * Never include the blank option, even if the underlying property is optional.
031         */
032        NEVER,
033    
034        /**
035         * The default: include the blank option if the underlying property is optional.
036         */
037        AUTO;
038    }