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.internal.transform;
014
015import org.apache.tapestry5.Binding;
016import org.apache.tapestry5.annotations.Parameter;
017import org.apache.tapestry5.commons.services.TypeCoercer;
018import org.apache.tapestry5.internal.InternalComponentResources;
019import org.apache.tapestry5.plastic.FieldConduit;
020
021/**
022 * A facade around {@link Binding} and {@link InternalComponentResources} that is used to instrument
023 * fields with the {@link Parameter} annotation. Extends {@link FieldConduit} so that
024 * the get() method implicitly coerces the value to the field's type.
025 *
026 * {@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
027 * parameter field's type. get() also includes a null value check (as per {@link Parameter#allowNull()}.
028 *
029 * {@link #set(Object, org.apache.tapestry5.plastic.InstanceContext, Object)} pushes the value into the binding.
030 *
031 * @since 5.2.0
032 */
033public interface ParameterConduit extends FieldConduit<Object>
034{
035    /**
036     * Determines if the parameter is actually bound.
037     *
038     * @return true if bound
039     */
040    boolean isBound();
041
042    /**
043     * Resets the conduit, clearing any <em>temporarily</em> cached data (from a non-invariant {@link Binding}).
044     */
045    void reset();
046}