001// Licensed under the Apache License, Version 2.0 (the "License");
002// you may not use this file except in compliance with the License.
003// You may obtain a copy of the License at
004//
005// http://www.apache.org/licenses/LICENSE-2.0
006//
007// Unless required by applicable law or agreed to in writing, software
008// distributed under the License is distributed on an "AS IS" BASIS,
009// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
010// See the License for the specific language governing permissions and
011// limitations under the License.
012
013package org.apache.tapestry5.annotations;
014
015import org.apache.tapestry5.internal.transform.BindParameterWorker;
016import org.apache.tapestry5.ioc.annotations.UseWith;
017
018import java.lang.annotation.ElementType;
019import java.lang.annotation.Retention;
020import java.lang.annotation.RetentionPolicy;
021import java.lang.annotation.Target;
022
023import static org.apache.tapestry5.ioc.annotations.AnnotationUseContext.MIXIN;
024
025/**
026 * Designates a field in a mixin which is bound to the parameter of the containing
027 * component corresponding to the value of the annotation. If no value is specified,
028 * the bound parameter name is assumed to match the field name of the mixin.
029 * For example, a mixin intended to work with form fields would define a field named
030 * "value", marked by this annotation. The user-variable bound to the component's value
031 * parameter would ultimately be bound in a chain:
032 * user-variable {@code <=>} mixin.value {@code <=>} component.value.
033 * Changes to any one value in the chain will be propagated accordingly.
034 * 
035 * @since 5.2.0
036 * @see BindParameterWorker
037 */
038@Target(ElementType.FIELD)
039@Retention(RetentionPolicy.RUNTIME)
040@UseWith(MIXIN)
041public @interface BindParameter
042{
043
044    /**
045     * @return the name of the mixin bound-parameter, exactly as for the Parameter annotation.
046     */
047    String name() default "";
048
049    /**
050     * @return the name(s) of the parent parameter to bind. Defaults to the name of the mixin field.
051     *         If more than one
052     *         name is specified, the first name matching a declared parameter of the core component
053     *         will be used.
054     */
055    String[] value() default
056    { "" };
057}