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
015package org.apache.tapestry5.corelib.components;
016
017import org.apache.tapestry5.Block;
018import org.apache.tapestry5.ComponentResources;
019import org.apache.tapestry5.annotations.InjectContainer;
020import org.apache.tapestry5.annotations.Parameter;
021import org.apache.tapestry5.annotations.SupportsInformalParameters;
022import org.apache.tapestry5.ioc.annotations.Inject;
023import 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
039public 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}