    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
    015    package org.apache.tapestry5.internal.transform;
    016
    017    import org.apache.tapestry5.Binding;
    018    import org.apache.tapestry5.annotations.Parameter;
    019    import org.apache.tapestry5.internal.InternalComponentResources;
    020    import org.apache.tapestry5.ioc.services.TypeCoercer;
    021    import 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     */
    035    public 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    }