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Basic functions

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/*
 * Copyright (c) 2007, 2019 Oracle and/or its affiliates. All rights reserved.
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Distribution License v. 1.0, which is available at
 * http://www.eclipse.org/org/documents/edl-v10.php.
 *
 * SPDX-License-Identifier: BSD-3-Clause
 */

package org.glassfish.pfl.basic.facet;

import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.util.Collection;

/** Interface to access facets of an object.  A facet is
 * an instance of a particular class.  It may be implemented
 * in a variety of ways, including inheritance, delegation,
 * or dynamic construction on demand.
 *
 * @author ken
 */
public interface FacetAccessor {
    /** Access the Facet of Class T from the object.
     * 
     * @param  The Type (as a Class) of the Facet.
     * @param cls The class of the facet.
     * @return Instance of cls for this facet.  Null if no such
     * facet is available.
     */
     T facet( Class cls ) ;
    
    /** Add a facet to the object.  The type T must not already
     * be available as a facet.
     * @param 
     * @param obj
     */
     void addFacet( T obj ) ;
    
    /** Remove the facet (if any) of the given type.
     * 
     * @param cls The class of the facet to remove.
     */
    void removeFacet( Class cls ) ;
    
    /** Return a list of all facets on this object.
     *
     * @return Collection of all facets.
     */
    Collection