001    // Copyright 2010, 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    
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    
049        /**
050         * Invoked from the component's {@link org.apache.tapestry5.runtime.PageLifecycleListener#containingPageDidLoad()} lifecycle method, to
051         * finishing initializing
052         * the conduit prior to real use.
053         */
054        void load();
055    }