All Downloads are FREE. Search and download functionalities are using the official Maven repository.

freemarker.template.TemplateModel Maven / Gradle / Ivy

There is a newer version: 7.0.58
Show newest version
/*
 * 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 freemarker.template;

import freemarker.template.utility.ClassUtil;

/**
 * The common super-interface of the interfaces that stand for the FreeMarker Template Language (FTL) data types.
 * The template language only deals with {@link TemplateModel}-s, not directly with plain Java objects. (For example,
 * it doesn't understand {@link java.lang.Number}, but {@link TemplateNumberModel}.) This is why the
 * data-model (aka. the "template context" in other languages) is (automatically) mapped to a tree of
 * {@link TemplateModel}-s.
 * 
 * 

Mapping the plain Java objects to {@link TemplateModel}-s (or the other way around sometimes) is the * responsibility of the {@link ObjectWrapper} (can be set via {@link Configuration#setObjectWrapper(ObjectWrapper)}). * But not all {@link TemplateModel}-s are for wrapping a plain object. For example, a value created within a template * is not made to wrap an earlier existing object; it's a value that has always existed in the template language's * domain. Users can also write {@link TemplateModel} implementations and put them directly into the data-model for * full control over how that object is seen from the template. Certain {@link TemplateModel} interfaces doesn't * even have equivalent in Java. For example the directive type ({@link TemplateDirectiveModel}) is like that. * *

Because {@link TemplateModel} "subclasses" are all interfaces, a value in the template language can have multiple * types. However, to prevent ambiguous situations, it's not recommended to make values that implement more than one of * these types: string, number, boolean, date. The intended applications are like string+hash, string+method, * hash+sequence, etc. * * @see ClassUtil#getFTLTypeDescription(TemplateModel) */ public interface TemplateModel { /** * A general-purpose object to represent nothing. It acts as * an empty string, false, empty sequence, empty hash, and * null-returning method model. */ TemplateModel NOTHING = GeneralPurposeNothing.getInstance(); }





© 2015 - 2024 Weber Informatics LLC | Privacy Policy