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Central module for Tapestry, containing interfaces to the Java Servlet API and all core services and components.

There is a newer version: 5.8.6

// Copyright 2010 The Apache Software Foundation
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package org.apache.tapestry5.internal.transform;

import org.apache.tapestry5.Binding;
import org.apache.tapestry5.annotations.Parameter;
import org.apache.tapestry5.internal.InternalComponentResources;
import org.apache.tapestry5.internal.bindings.LiteralBinding;
import org.apache.tapestry5.ioc.services.FieldValueConduit;
import org.apache.tapestry5.ioc.services.TypeCoercer;
import org.apache.tapestry5.runtime.Component;

/**
 * A facade around {@link Binding} and {@link InternalComponentResources} that is used to instrument
 * fields with the {@link Parameter} annotation. Extends {@link FieldValueConduit} so that
 * the get() method implicitly coerces the value to the field's type.
 * 
 * {@link #get()} will read from the underlying {@link Binding} and used the {@link TypeCoercer} coerce the value to the
 * parameter field's type. get() also includes a null value check (as per {@link Parameter#allowNull()}.
 * 
 * {@link #set(Object)} pushes the value into the binding.
 * 
 * @since 5.2.0
 */
public interface ParameterConduit extends FieldValueConduit
{
    /**
     * Sets the default value for the parameter based on either the current value of the field,
     * or on result from a default method. This is only used if the parameter is not otherwise
     * bound.
     * 
     * @param defaultValue
     *            an object (which will be wrapped as a {@link LiteralBinding}, or
     *            a {@link Binding} instance
     */
    void setDefault(Object defaultValue);

    /**
     * Determines if the parameter is actually bound.
     * 
     * @return
     */
    boolean isBound();

    /**
     * Resets the conduit, clearing any temporarily cached data (from a non-invariant {@link Binding}).
     */
    void reset();

    /**
     * Invoked from the component's {@link Component#containingPageDidLoad()} lifecycle method, to
     * finishing initializing
     * the conduit prior to real use.
     */
    void load();
}