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

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

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

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

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

<!-- Initial Contributors:

    Nokia Corporation - initial contribution.

Contributors: 

-->

<!DOCTYPE task

  PUBLIC "-//OASIS//DTD DITA Task//EN" "task.dtd">

<task id="GUID-69D916D3-ED05-58DA-BA42-CE4D7E4F6482" xml:lang="en"><title>Automatic

Resource Management Class Templates Tutorial</title><abstract>The <codeph>LCleanedupX</codeph> class provide a means of automatically

cleaning up local variables on scope exit. Variants are provided for cleaning

up pointers, references, handles and arrays, as well as generic cleanup items.

The user is able to define a cleanup strategy to clean up the resource on

scope exit.</abstract><prolog><metadata><keywords/></metadata></prolog><taskbody>

<prereq><p>Before beginning you must know the following: </p><ul>

<li id="GUID-90A3678E-CB31-5817-AB27-C115AC486A3A"><p> <b> Clean-up Stratergy:</b> Cleanup

strategies can be specified as an optional template parameter of the class

templates for automatic resource management. </p> </li>

</ul> </prereq>

<steps-unordered>

<step id="GUID-26218FF0-6994-4FD7-9609-357AFDB3C177"><cmd><b>Declaring an LCleanedupX object</b></cmd>

<info><p>An <codeph>LCleanedupX</codeph> object is declared using one of the

class template constructors. The type to be managed is declared as the first

template parameter. An optional second template parameter can be declared

to implement a non-default cleanup strategy. </p> <p>An example code snippet

for declaring <codeph>LCleanedupX</codeph> class is shown below: </p> <codeblock id="GUID-B9DFC2F9-0C7A-5CCA-9125-FC165BFA6C1B" xml:space="preserve">class LCleanedupPtr

            {

            CTicker* ticker1 = new(ELeave) CTicker;

            LCleanedupPtr CManagedUserTwoPhase one(CManagedUserTwoPhase::NewL(ticker1));

            CTicker* ticker2 = new(ELeave) CTicker;

            LCleanedupPtr CManagedUserSinglePhase two(CManagedUserSinglePhase::NewL(ticker2));

        }

</codeblock></info>

</step>

<step id="GUID-AF65DC71-78C1-4B4D-9546-A9F4921E89D9"><cmd><b>Disabling Automatic Cleanup</b></cmd>

<info><p>An object that is being managed by an <codeph>LCleanedupX</codeph> class

can be unmanaged by calling the <codeph>Unmanage()</codeph> method of the

LCleanedupX class. </p> <p>The managing object can be accessed using the .

operator as in the call to <codeph>Unmanage()</codeph>. The <codeph>Unmanage()</codeph> disables

cleanup and yields the previously managed pointer so that it can be safely

returned. </p> <p>An example code snippet is given below: </p> <codeblock id="GUID-75BA5FAF-4C81-5626-A1F6-8AF91FD5972E" xml:space="preserve">

        static CStringUserTwoPhase* NewL(const TDesC& aName)

            {

                LCleanedupPtr CStringUserTwoPhase self(new(ELeave) CStringUserTwoPhase);

                self->ConstructL(aName);

                return self.Unmanage(); 

            }

</codeblock></info>

</step>

<step id="GUID-B9F7C183-E92E-47D6-8A6E-A1E1A76C1253"><cmd><b>Accessing the managed object</b></cmd>

<info><p>The managed object can be accessed using the -&gt; operator as in the

call to <codeph>ConstructL()</codeph> </p> <codeblock id="GUID-2C82F4C0-9E02-51C5-BF51-2C05EACB424C" xml:space="preserve">self-&gt;ConstructL(aName);</codeblock></info>

</step>

<step id="GUID-D070D636-665B-4023-A81A-C5AB0A5390CB"><cmd><b>Passing the managed object to a function</b></cmd>

<info><p>The managed object can be passed to a function by dereferencing the

managing object. An example code snippet is given below: </p> <codeblock id="GUID-5E5A3A0C-77E4-520A-BD0A-031C7D3CAAFD" xml:space="preserve">

void RegisterTicker(CTicker& aTicker)

    {

    (void)aTicker;

    }

</codeblock><p>The <codeph>RegisterTicker</codeph> function defined above

takes a <codeph>CTicker&amp;</codeph> argument. If we have a <codeph>LCleanedupPtr&lt;CTicker&gt;</codeph> as

defined below, we can pass the <codeph>CTicker</codeph> object to the function

by dereferencing as shown below in the code snippet: </p> <codeblock id="GUID-EC93EC4F-3D3E-5A70-A0E1-CF73475A7309" xml:space="preserve">

LCleanedupPtr CTicker t(new(ELeave) CTicker);

RegisterTicker(*t); // Takes a CTicker&

</codeblock></info>

</step>

</steps-unordered>

</taskbody><related-links>

<link href="GUID-B1D5B680-00E3-5702-985A-94256180E2D8.dita"><linktext>Automatic

Resource Management</linktext></link>

<link href="GUID-B419D99E-8312-5336-9693-3ED8DFCD0559.dita"><linktext>Automatic

Resource Management Tutorial</linktext></link>