1 <?xml version="1.0" encoding="utf-8"?>

     2 <!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->

     3 <!-- This component and the accompanying materials are made available under the terms of the License 

     4 "Eclipse Public License v1.0" which accompanies this distribution, 

     5 and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->

     6 <!-- Initial Contributors:

     7     Nokia Corporation - initial contribution.

     8 Contributors: 

     9 -->

    10 <!DOCTYPE concept

    11   PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

    12 <concept id="GUID-1D9376CD-3160-5CD8-A138-B94C5F7A50F8" xml:lang="en"><title>Using

    13 MUTABLE_CAST macro</title><shortdesc>This topic explains how to cast away the constant of the counter

    14 variable.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

    15 <p>In the example code below, the class has a simple const getter function <codeph>Var()</codeph>.

    16 It uses <codeph>MUTABLE_CAST</codeph> to cast away the <codeph>const</codeph> -ness

    17 of the counter variable <codeph>iGetCounter</codeph>, which allows that variable

    18 to be changed.</p>

    19 <codeblock id="GUID-8EA00511-AA50-5401-B13D-D21C4611B22F" xml:space="preserve">class TMutableDemo 

    20  {

    21 public:

    22  TMutableDemo(TUint a=0):iVar(a),iGetCounter(0) {};

    23  TUint Var() const;

    24  

    25 private:

    26  TUint iVar;

    27  __MUTABLE TUint iGetCounter;

    28  };

    29 

    30 TUint TMutableDemo::Var() const 

    31  {

    32  MUTABLE_CAST(TMutableDemo*,this)->iGetCounter++;

    33  return iVar; 

    34  }</codeblock>

    35 </conbody></concept>