gecko-dev/xpcom/base/nsIInterfaceRequestor.idl

/* -*- Mode: IDL; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsISupports.idl"

/**
 * The nsIInterfaceRequestor interface defines a generic interface for 
 * requesting interfaces that a given object might provide access to.
 * This is very similar to QueryInterface found in nsISupports.  
 * The main difference is that interfaces returned from GetInterface()
 * are not required to provide a way back to the object implementing this 
 * interface.  The semantics of QI() dictate that given an interface A that 
 * you QI() on to get to interface B, you must be able to QI on B to get back 
 * to A.  This interface however allows you to obtain an interface C from A 
 * that may or most likely will not have the ability to get back to A. 
 */

[scriptable, uuid(033A1470-8B2A-11d3-AF88-00A024FFC08C)]
interface nsIInterfaceRequestor : nsISupports
{
   /**
    * Retrieves the specified interface pointer.
    *
    * @param uuid The IID of the interface being requested.
    * @param result [out] The interface pointer to be filled in if
    *               the interface is accessible.
    * @throws NS_NOINTERFACE - interface not accessible.
    * @throws NS_ERROR* - method failure.
    */
	void getInterface(in nsIIDRef uuid, 
                      [iid_is(uuid),retval] out nsQIResult result);
};