xpcom/base/nsIWeakReference.idl

   1 /* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
   2  *
   3  * ***** BEGIN LICENSE BLOCK *****
   4  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   5  *
   6  * The contents of this file are subject to the Mozilla Public License Version
   7  * 1.1 (the "License"); you may not use this file except in compliance with
   8  * the License. You may obtain a copy of the License at
   9  * http://www.mozilla.org/MPL/
  10  *
  11  * Software distributed under the License is distributed on an "AS IS" basis,
  12  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  13  * for the specific language governing rights and limitations under the
  14  * License.
  15  *
  16  * The Original Code is the Mozilla browser.
  17  *
  18  * The Initial Developer of the Original Code is
  19  * Netscape Communications, Inc.
  20  * Portions created by the Initial Developer are Copyright (C) 1999
  21  * the Initial Developer. All Rights Reserved.
  22  *
  23  * Contributor(s):
  24  *   Pierre Phaneuf <pp@ludusdesign.com>
  25  *
  26  * Alternatively, the contents of this file may be used under the terms of
  27  * either of the GNU General Public License Version 2 or later (the "GPL"),
  28  * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  29  * in which case the provisions of the GPL or the LGPL are applicable instead
  30  * of those above. If you wish to allow use of your version of this file only
  31  * under the terms of either the GPL or the LGPL, and not to allow others to
  32  * use your version of this file under the terms of the MPL, indicate your
  33  * decision by deleting the provisions above and replace them with the notice
  34  * and other provisions required by the GPL or the LGPL. If you do not delete
  35  * the provisions above, a recipient may use your version of this file under
  36  * the terms of any one of the MPL, the GPL or the LGPL.
  37  *
  38  * ***** END LICENSE BLOCK ***** */
  39
  40 #include "nsISupports.idl"
  41
  42
  43 /**
  44  * An instance of |nsIWeakReference| is a proxy object that cooperates with
  45  * its referent to give clients a non-owning, non-dangling reference.  Clients
  46  * own the proxy, and should generally manage it with an |nsCOMPtr| (see the
  47  * type |nsWeakPtr| for a |typedef| name that stands out) as they would any
  48  * other XPCOM object.  The |QueryReferent| member function provides a
  49  * (hopefully short-lived) owning reference on demand, through which clients
  50  * can get useful access to the referent, while it still exists.
  51  *
  52  * @status FROZEN
  53  * @version 1.0
  54  * @see nsISupportsWeakReference
  55  * @see nsWeakReference
  56  * @see nsWeakPtr
  57  */
  58 [scriptable, uuid(9188bc85-f92e-11d2-81ef-0060083a0bcf)]
  59 interface nsIWeakReference : nsISupports
  60   {
  61     /**
  62      * |QueryReferent| queries the referent, if it exists, and like |QueryInterface|, produces
  63      * an owning reference to the desired interface.  It is designed to look and act exactly
  64      * like (a proxied) |QueryInterface|.  Don't hold on to the produced interface permanently;
  65      * that would defeat the purpose of using a non-owning |nsIWeakReference| in the first place.
  66      */
  67     void QueryReferent( in nsIIDRef uuid, [iid_is(uuid), retval] out nsQIResult result );
  68   };
  69
  70
  71 /**
  72  * |nsISupportsWeakReference| is a factory interface which produces appropriate
  73  * instances of |nsIWeakReference|.  Weak references in this scheme can only be
  74  * produced for objects that implement this interface.
  75  *
  76  * @status FROZEN
  77  * @version 1.0
  78  * @see nsIWeakReference
  79  * @see nsSupportsWeakReference
  80  */
  81 [scriptable, uuid(9188bc86-f92e-11d2-81ef-0060083a0bcf)]
  82 interface nsISupportsWeakReference : nsISupports
  83   {
  84     /**
  85      * |GetWeakReference| produces an appropriate instance of |nsIWeakReference|.
  86      * As with all good XPCOM `getters', you own the resulting interface and should
  87      * manage it with an |nsCOMPtr|.
  88      *
  89      * @see nsIWeakReference
  90      * @see nsWeakPtr
  91      * @see nsCOMPtr
  92      */
  93     nsIWeakReference GetWeakReference();
  94   };
  95
  96
  97 %{C++
  98 #ifdef MOZILLA_INTERNAL_API
  99 #include "nsIWeakReferenceUtils.h"
 100 #endif
 101 %}
 102