001    // Copyright 2007, 2008, 2011 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.components;
016    
017    import org.apache.tapestry5.Block;
018    import org.apache.tapestry5.ComponentResources;
019    import org.apache.tapestry5.annotations.InjectContainer;
020    import org.apache.tapestry5.annotations.Parameter;
021    import org.apache.tapestry5.annotations.SupportsInformalParameters;
022    import org.apache.tapestry5.ioc.annotations.Inject;
023    import org.apache.tapestry5.runtime.Component;
024    
025    /**
026     * A component that does not do any rendering of its own, but will delegate to some other object that can do rendering.
027     * This other object may be a component or a {@link Block} (among other things).
028     * <p>
029     * This component may also be used to create inline components. For each informal parameter the value will be stored as a 
030     * render variable. To create an inline component, create a block
031     * and use Delegate multiple times in the template to render the block passing parameters to Delegate. In the block body
032     * reference the render variables using the "var:" binding prefix and the name of the parameter.
033     * <p>
034     * Note that the default binding prefix for informal parameter values is "literal".
035     * 
036     * @tapestrydoc
037     */
038    @SupportsInformalParameters
039    public class Delegate
040    {
041        /**
042         * The object which will be rendered in place of the Delegate component. This is typically a specific component
043         * instance, or a {@link Block}.
044         */
045        @Parameter(required = true)
046        private Object to;
047    
048            @Inject private ComponentResources resources;
049            @InjectContainer private Component container;
050            
051            Object beginRender()
052            {
053            for(String name : resources.getInformalParameterNames()) {
054                    Object value = resources.getInformalParameter(name, Object.class);
055                    container.getComponentResources().storeRenderVariable(name, value);
056            }
057            
058            return to;
059        }
060    }