Symbian3/SDK/Source/GUID-0715E8B9-8F43-5C7B-BDC6-4E8FA5352714.dita
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--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Symbian3/SDK/Source/GUID-0715E8B9-8F43-5C7B-BDC6-4E8FA5352714.dita	Thu Jan 21 18:18:20 2010 +0000
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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 concept
+  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
+<concept id="GUID-0715E8B9-8F43-5C7B-BDC6-4E8FA5352714" xml:lang="en"><title>Cleanup
+following trap harnesses</title><shortdesc>Some cleanup requirements must be handled by the cleanup code after
+the trap harness.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
+<p>Some cleanup requirements must be handled by the cleanup code after the
+trap harness, on discovering that the leave code is not <codeph>KErrNone</codeph>.
+The cleanup requirements may include:</p>
+<ul>
+<li id="GUID-3F81400F-8343-50A9-9076-D342AB8FA85C"><p>rolling back changes
+to restore an object to the state it was in before the function which left
+was invoked</p> <p>For instance, a “set font” command might have been issued
+for some characters in a line, and might fail because of lack of memory: the
+line should be restored to its previous state.</p> <p>Rollback is not always
+easy. Often, it’s simpler to prepare a change that would be guaranteed to
+work, and apply it if the change was prepared successfully. If a leave occurred
+in the act of preparing a change, the change can be destroyed. It’s usually
+easier to destroy a change than to roll it back.</p> </li>
+</ul>
+<ul>
+<li id="GUID-CD29C562-17AE-50D6-A629-FFCE70B60545"><p>destroying a partially-constructed
+object</p> <p>Most requirements for destroying partially-constructed objects
+will be dealt with by the cleanup stack. There may be a requirement to destroy
+some partially-constructed objects as part of rollback processing. </p> </li>
+</ul>
+<ul>
+<li id="GUID-4E8F6B7C-009E-5EC6-BBB9-A737B16CDBBD"><p>closing files and other
+such resources, where this is not encapsulated in use of the cleanup stack.</p> </li>
+</ul>
+</conbody></concept>
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