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+<?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-3799F0DA-B99C-55BB-B44F-63B971DF1865" xml:lang="en"><title>Cleanup
+Strategy Tutorial</title><shortdesc>This tutorial describes the cleanup strategy and provides details
+on alternative cleanup strategies. </shortdesc><prolog><metadata><keywords/></metadata></prolog><taskbody>
+<prereq><p>Before you start, you must: </p> <ul>
+<li id="GUID-18CD0776-EEA9-56AF-9E5F-E5101BB88643"><p> <b>Deafult cleanup
+strategies:</b> These are based on a template-based implementation of the
+strategy design pattern. </p> </li>
+<li id="GUID-598FF730-0C91-51C4-B9AA-16B74137BB6E"><p> <b>Alternative cleanup
+strategies:</b> These can be specified as an optional template parameter of
+the class templates for automatic resource management. </p> </li>
+</ul> </prereq>
+<context><p>Cleanup strategy is based on a template-based implementation of
+the Strategy design pattern. The strategy design pattern is one of the most
+popular, highly recommended design patterns. The vast majority of the competent
+C++ developers are already familiar with the strategy (Policy) design pattern
+and Policy-based design, which should improve the usability of these class
+templates. </p> <p>Each
+resource management class has a default cleanup strategy that is invoked when
+the managing object goes out of scope. It is however possible to define an
+alternative cleanup strategy when constructing the managing object. It is
+also possible to define a custom cleanup strategy using the <xref href="GUID-CE0F22BA-8789-3659-87C4-164EB5862B4C.dita"><apiname>DEFINE_CLEANUP_FUNCTION</apiname></xref> macro. </p> <p> <b>Note:</b> Although
+the examples below use LCleanedupX classes, the method for definfing how the
+object is cleaned up is equally applicable to LManagedX classes. </p> <p>An
+example code snippet is given below: </p> <codeblock id="GUID-DE45C250-C8C5-5210-B53C-D9256F00194B" xml:space="preserve">
+//Class definition of trivial R-Class
+class RSimple
+ {
+public:
+
+ RSimple(){iData = NULL;}
+
+ void Open(TInt aValue)
+ {
+ iData = new(ELeave) TInt(aValue);
+ }
+
+ //Cleanup function – frees resource
+ void Close()
+ {
+ delete iData;
+ iData = NULL;
+ }
+
+ //Cleanup function – frees resource
+ void Free()
+ {
+ delete iData;
+ iData = NULL;
+ }
+
+ //Cleanup function – frees resource
+ void ReleaseData()
+ {
+ delete iData;
+ iData = NULL;
+ }
+
+ //static cleanup function – frees aRSimple resources
+ static void Cleanup(TAny* aRSimple)
+ {
+ static_cast RSimple* (aRSimple)->Close();
+ }
+private:
+ Tint* iData;
+
+ };
+
+</codeblock> <p>The above RSimple class has three cleanup member functions,
+Close, Free and ReleaseData. </p> <p>Each resource management class has a
+default cleanup strategy that is invoked when the managing object goes out
+of scope. The default cleanup strategy is dependent on the managing type.
+Consider the example code snippet below: </p> <p> <b>Note:</b> Although the
+examples below use LManagedX classes, the method for defining a custom cleanup
+strategy is equally applicable to LCleanedupX classes. </p> <codeblock id="GUID-7D4F639F-3BEA-59CD-BA75-DF1C25175BA3" xml:space="preserve">
+class CTicker : public CBase
+ {
+public:
+ void Tick() { ++iTicks; }
+ void Tock() { ++iTocks; }
+
+ void Zap() { delete this; }
+
+public:
+ TInt iTicks;
+ TInt iTocks;
+ };
+
+
+class CManagedUserSinglePhase : public CBase
+ {
+public:
+ . . .
+
+ ~CManagedUserSinglePhase()
+ {
+ // The iTicker manager will automatically delete the CTicker
+ // The iTimer manager will automatically Close() the RTimer
+ }
+
+ . . .
+private:
+ // We have to use LManagedXxx for fields, not LCleanedupXxx
+ LManagedPtr CTicker iTicker;
+ LManagedHandle RTimer iTimer;
+ };
+</codeblock> <p>The default cleanup strategy for an LManagedPtr is to delete
+the pointer and this is the action taken in the destructor for CManagedUserSinglePhase. </p> <p>Alternate
+cleanup strategies are pre-defined in <filepath>emanaged.h</filepath> file.
+It is also possible to define a custom alternate cleanup strategy that can
+be passed as the second template parameter to the constructor of an LManagedX
+or LCleanedupX object. </p> <p>Although the examples below use LManagedX classes,
+the method for defining an alternate cleanup strategy is equally applicable
+to LCleanedupX classes. </p> <p>The default cleanup strategy is to call <xref href="GUID-91F3C4E0-5687-366D-9D50-D710E763F0CF.dita#GUID-91F3C4E0-5687-366D-9D50-D710E763F0CF/GUID-29E73AC7-D397-3237-ABF9-C93C0AD39543"><apiname>CTicker::Zap()</apiname></xref> function.
+It is possible however to define a custom alternate cleanup strategy as shown
+below: </p> <codeblock id="GUID-5B268C52-2708-50CF-8070-0896C8CE80C0" xml:space="preserve">
+// Defines a custom pointer cleanup policy that calls the Zap member
+template <class T>
+class TTickerZap
+ {
+public:
+ static void Cleanup(T* aPtr)
+ {
+ // The general template/class scaffolding remains the same
+ // for all custom cleanups, just this cleanup body varies
+ aPtr->Zap();
+ test.Printf(_L("Zapped CTicker\n"));
+ }
+ };
+</codeblock> </context>
+</taskbody><related-links>
+<link href="GUID-B007634D-4D55-528A-8B85-6120C633AC8B.dita"><linktext>EUser High
+Level Overview</linktext></link>
+<link href="GUID-A18153C0-230C-51FB-9384-A48BB4E42F03.dita"><linktext>Clean-up
+Strategy</linktext></link>
+</related-links></task>
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