Symbian3/PDK/Source/GUID-FE138F1A-1F52-5E9A-8EB2-5A8945A9CF30.dita
author Graeme Price <GRAEME.PRICE@NOKIA.COM>
Fri, 15 Oct 2010 14:32:18 +0100
changeset 15 307f4279f433
parent 14 578be2adaf3e
permissions -rw-r--r--
Initial contribution of the Adaptation Documentation.
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
14
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
     1
<?xml version="1.0" encoding="utf-8"?>
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
     2
<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
     3
<!-- This component and the accompanying materials are made available under the terms of the License 
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
     4
"Eclipse Public License v1.0" which accompanies this distribution, 
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
     5
and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
     6
<!-- Initial Contributors:
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
     7
    Nokia Corporation - initial contribution.
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
     8
Contributors: 
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
     9
-->
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    10
<!DOCTYPE concept
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    11
  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    12
<concept id="GUID-FE138F1A-1F52-5E9A-8EB2-5A8945A9CF30" xml:lang="en"><title>Destructor
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    13
requirements</title><shortdesc>This document describes cleanup actions required for C type and
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    14
other classes.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    15
<p>For <codeph>C</codeph> type classes, cleanup invokes the destructor. For
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    16
other types of object, other actions may be required. </p>
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    17
<p>The destructor for <codeph>C</codeph> type classes must be coded to release
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    18
all resources owned by the object. By definition, cleanup may occur on <i>partially</i> constructed
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    19
objects: the destructor may not, therefore, assume that all conditions for
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    20
a fully-constructed object hold in these circumstances. A typical situation
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    21
to watch for is calling a member function on a pointer that is initialized
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    22
in the <codeph>ConstructL()</codeph>, as the pointer could be <codeph>NULL</codeph> in
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    23
failure cases.</p>
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    24
<p>Resources will usually be indicated by pointers or handles. It is important
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    25
that such pointers or handles are null when there is no resource allocated,
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    26
and that the destructor test for a non-null value before destroying them.</p>
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    27
<p>This behaviour is facilitated in <codeph>CBase</codeph> -derived classes,
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    28
because their memory is guaranteed to be initially set to binary zeroes when
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    29
they are first allocated.</p>
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    30
<p>Programmers must, however, take particular care with pointers which are
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    31
used for owned objects which are repeatedly allocated and de-allocated throughout
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    32
an object’s lifetime. When such owned objects are de-allocated, the pointer
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    33
should always immediately be set to null.</p>
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    34
<section id="GUID-DFAB4D8D-FD81-4754-9472-2BCFD8B90F9E"><title>See also</title> <p><xref href="GUID-7366AE99-DE25-5DE0-BF9A-58E7742DA952.dita">Advanced
578be2adaf3e Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
Dominic Pinkman <dominic.pinkman@nokia.com>
parents: 5
diff changeset
    35
Cleanup</xref>.</p> </section>
1
25a17d01db0c Addition of the PDK content and example code for Documentation_content according to Feature bug 1607 and bug 1608
Dominic Pinkman <Dominic.Pinkman@Nokia.com>
parents:
diff changeset
    36
</conbody></concept>