    001// Copyright 2010, 2011, 2012 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.internal.transform;
    016
    017import org.apache.tapestry5.Binding;
    018import org.apache.tapestry5.annotations.Parameter;
    019import org.apache.tapestry5.internal.InternalComponentResources;
    020import org.apache.tapestry5.ioc.services.TypeCoercer;
    021import org.apache.tapestry5.plastic.FieldConduit;
    022
    023/**
    024 * A facade around {@link Binding} and {@link InternalComponentResources} that is used to instrument
    025 * fields with the {@link Parameter} annotation. Extends {@link FieldConduit} so that
    026 * the get() method implicitly coerces the value to the field's type.
    027 * <p/>
    028 * {@link #get(Object, org.apache.tapestry5.plastic.InstanceContext)} will read from the underlying {@link Binding} and used the {@link TypeCoercer} coerce the value to the
    029 * parameter field's type. get() also includes a null value check (as per {@link Parameter#allowNull()}.
    030 * <p/>
    031 * {@link #set(Object, org.apache.tapestry5.plastic.InstanceContext, Object)} pushes the value into the binding.
    032 *
    033 * @since 5.2.0
    034 */
    035public interface ParameterConduit extends FieldConduit<Object>
    036{
    037    /**
    038     * Determines if the parameter is actually bound.
    039     *
    040     * @return true if bound
    041     */
    042    boolean isBound();
    043
    044    /**
    045     * Resets the conduit, clearing any <em>temporarily</em> cached data (from a non-invariant {@link Binding}).
    046     */
    047    void reset();
    048}