Symbian3/Examples/guid-6013a680-57f9-415b-8851-c4fa63356636/_m_classes3_8cpp_source.html
Week 32 contribution of PDK documentation content. See release notes for details. Fixes bug Bug 3582
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<h1>examples/Basics/MClasses3/MClasses3.cpp</h1><div class="fragment"><pre class="fragment"><a name="l00001"></a>00001 <span class="comment">// Copyright (c) 1997-2009 Nokia Corporation and/or its subsidiary(-ies).</span>
<a name="l00002"></a>00002 <span class="comment">// All rights reserved.</span>
<a name="l00003"></a>00003 <span class="comment">// This component and the accompanying materials are made available</span>
<a name="l00004"></a>00004 <span class="comment">// under the terms of "Eclipse Public License v1.0"</span>
<a name="l00005"></a>00005 <span class="comment">// which accompanies this distribution, and is available</span>
<a name="l00006"></a>00006 <span class="comment">// at the URL "http://www.eclipse.org/legal/epl-v10.html".</span>
<a name="l00007"></a>00007 <span class="comment">//</span>
<a name="l00008"></a>00008 <span class="comment">// Initial Contributors:</span>
<a name="l00009"></a>00009 <span class="comment">// Nokia Corporation - initial contribution.</span>
<a name="l00010"></a>00010 <span class="comment">//</span>
<a name="l00011"></a>00011 <span class="comment">// Contributors:</span>
<a name="l00012"></a>00012 <span class="comment">//</span>
<a name="l00013"></a>00013 <span class="comment">// Description:</span>
<a name="l00014"></a>00014 <span class="comment">// Demonstrate use of M classes, or mixins - the</span>
<a name="l00015"></a>00015 <span class="comment">// only use of multiple inheritance that has been</span>
<a name="l00016"></a>00016 <span class="comment">// sanctioned by the E32 architecture team</span>
<a name="l00017"></a>00017 <span class="comment">// This example shows how mixins can be used to</span>
<a name="l00018"></a>00018 <span class="comment">// pass some protocol, and an associated object, from</span>
<a name="l00019"></a>00019 <span class="comment">// a protocol provider to an protocol user. The user</span>
<a name="l00020"></a>00020 <span class="comment">// is not supposed to know everything about the provider,</span>
<a name="l00021"></a>00021 <span class="comment">// only about the protocol it's interested in.</span>
<a name="l00022"></a>00022 <span class="comment">// In this specific example, the provider is derived from</span>
<a name="l00023"></a>00023 <span class="comment">// an appropriate base class, and a mixin class representing</span>
<a name="l00024"></a>00024 <span class="comment">// the protocol. The benefits of the method shown in example EUTYPEM2</span>
<a name="l00025"></a>00025 <span class="comment">// are thus gained, without the inconvenience of intermediary</span>
<a name="l00026"></a>00026 <span class="comment">// classes.</span>
<a name="l00027"></a>00027 <span class="comment">//</span>
<a name="l00028"></a>00028
<a name="l00029"></a>00029
<a name="l00030"></a>00030
<a name="l00031"></a>00031 <span class="preprocessor">#include "CommonFramework.h"</span>
<a name="l00032"></a>00032
<a name="l00034"></a>00034 <span class="comment">//</span>
<a name="l00035"></a>00035 <span class="comment">// -----> CProtocol (definition)</span>
<a name="l00036"></a>00036 <span class="comment">//</span>
<a name="l00037"></a>00037 <span class="comment">// A protocol class for mixing in</span>
<a name="l00038"></a>00038 <span class="comment">//</span>
<a name="l00040"></a>00040 <span class="comment"></span><span class="keyword">class </span>MProtocol
<a name="l00041"></a>00041 {
<a name="l00042"></a>00042 <span class="keyword">public</span>:
<a name="l00043"></a>00043 <span class="keyword">virtual</span> <span class="keywordtype">void</span> HandleEvent(TInt aEventCode)=0;
<a name="l00044"></a>00044 };
<a name="l00045"></a>00045
<a name="l00046"></a>00046
<a name="l00048"></a>00048 <span class="comment">//</span>
<a name="l00049"></a>00049 <span class="comment">// -----> CProtocolUser (definition)</span>
<a name="l00050"></a>00050 <span class="comment">//</span>
<a name="l00051"></a>00051 <span class="comment">// Define a protocol user which uses this protocol</span>
<a name="l00052"></a>00052 <span class="comment">//</span>
<a name="l00054"></a>00054 <span class="comment"></span><span class="keyword">class </span>CProtocolUser : <span class="keyword">public</span> CBase
<a name="l00055"></a>00055 {
<a name="l00056"></a>00056 <span class="keyword">public</span>:
<a name="l00057"></a>00057 <span class="comment">// Construction</span>
<a name="l00058"></a>00058 <span class="keyword">static</span> CProtocolUser* NewLC();
<a name="l00059"></a>00059 <span class="keyword">static</span> CProtocolUser* NewL();
<a name="l00060"></a>00060
<a name="l00061"></a>00061 <span class="comment">// Destruction</span>
<a name="l00062"></a>00062 ~CProtocolUser();
<a name="l00063"></a>00063
<a name="l00064"></a>00064 <span class="comment">// Some function which uses a protocol</span>
<a name="l00065"></a>00065 <span class="keywordtype">void</span> DoSomething(MProtocol* aProtocol);
<a name="l00066"></a>00066
<a name="l00067"></a>00067 <span class="keyword">protected</span>:
<a name="l00068"></a>00068 <span class="comment">// Construction assistance</span>
<a name="l00069"></a>00069 <span class="keywordtype">void</span> ConstructL();
<a name="l00070"></a>00070 };
<a name="l00071"></a>00071
<a name="l00072"></a>00072
<a name="l00074"></a>00074 <span class="comment">//</span>
<a name="l00075"></a>00075 <span class="comment">// -----> CProtocolProvider (definition)</span>
<a name="l00076"></a>00076 <span class="comment">//</span>
<a name="l00077"></a>00077 <span class="comment">// A simple class which uses the mixin</span>
<a name="l00078"></a>00078 <span class="comment">//</span>
<a name="l00080"></a>00080 <span class="comment"></span><span class="keyword">class </span>CProtocolProvider : <span class="keyword">public</span> CBase, <span class="keyword">public</span> MProtocol
<a name="l00081"></a>00081 {
<a name="l00082"></a>00082 <span class="keyword">public</span>:
<a name="l00083"></a>00083 <span class="comment">// Construction</span>
<a name="l00084"></a>00084 <span class="keyword">static</span> CProtocolProvider* NewLC();
<a name="l00085"></a>00085
<a name="l00086"></a>00086 <span class="comment">// Destruction</span>
<a name="l00087"></a>00087 ~CProtocolProvider();
<a name="l00088"></a>00088
<a name="l00089"></a>00089 <span class="comment">// Calls the protocol user</span>
<a name="l00090"></a>00090 <span class="keywordtype">void</span> CallProtocolUser();
<a name="l00091"></a>00091
<a name="l00092"></a>00092 <span class="comment">// Implement the protocol (handles the protocol)</span>
<a name="l00093"></a>00093 <span class="keywordtype">void</span> HandleEvent(TInt aEventCode);
<a name="l00094"></a>00094
<a name="l00095"></a>00095 <span class="keyword">protected</span>:
<a name="l00096"></a>00096 <span class="comment">// Construction assistance</span>
<a name="l00097"></a>00097 <span class="keywordtype">void</span> ConstructL();
<a name="l00098"></a>00098
<a name="l00099"></a>00099 <span class="keyword">private</span>:
<a name="l00100"></a>00100 <span class="comment">// data members defined by this class</span>
<a name="l00101"></a>00101 CProtocolUser* iProtocolUser;
<a name="l00102"></a>00102 };
<a name="l00103"></a>00103
<a name="l00104"></a>00104
<a name="l00106"></a>00106 <span class="comment">//</span>
<a name="l00107"></a>00107 <span class="comment">// -----> CProtocolUser (implementation)</span>
<a name="l00108"></a>00108 <span class="comment">//</span>
<a name="l00110"></a>00110 <span class="comment"></span>CProtocolUser* CProtocolUser::NewLC()
<a name="l00111"></a>00111 {
<a name="l00112"></a>00112 CProtocolUser* <span class="keyword">self</span>=<span class="keyword">new</span>(ELeave) CProtocolUser;
<a name="l00113"></a>00113 CleanupStack::PushL(<span class="keyword">self</span>);
<a name="l00114"></a>00114 <span class="keyword">self</span>->ConstructL();
<a name="l00115"></a>00115 <span class="keywordflow">return</span> <span class="keyword">self</span>;
<a name="l00116"></a>00116 }
<a name="l00117"></a>00117
<a name="l00118"></a>00118 CProtocolUser* CProtocolUser::NewL()
<a name="l00119"></a>00119 {
<a name="l00120"></a>00120 CProtocolUser* <span class="keyword">self</span>=NewLC();
<a name="l00121"></a>00121 CleanupStack::Pop();
<a name="l00122"></a>00122 <span class="keywordflow">return</span> <span class="keyword">self</span>;
<a name="l00123"></a>00123 }
<a name="l00124"></a>00124
<a name="l00125"></a>00125 CProtocolUser::~CProtocolUser()
<a name="l00126"></a>00126 {
<a name="l00127"></a>00127 }
<a name="l00128"></a>00128
<a name="l00129"></a>00129 <span class="keywordtype">void</span> CProtocolUser::ConstructL()
<a name="l00130"></a>00130 {
<a name="l00131"></a>00131 }
<a name="l00132"></a>00132
<a name="l00133"></a>00133 <span class="keywordtype">void</span> CProtocolUser::DoSomething(MProtocol* aProtocol)
<a name="l00134"></a>00134 {
<a name="l00135"></a>00135 <span class="comment">// Do something that requires a protocol</span>
<a name="l00136"></a>00136 <a class="code" href="secureclientandserver_8h.html#a5eadd4429627d82193b37536d4faa03a">_LIT</a>(KTxtExtSystemDoing,<span class="stringliteral">"External system doing something\n"</span>);
<a name="l00137"></a>00137 console->Printf(KTxtExtSystemDoing);
<a name="l00138"></a>00138 <a class="code" href="secureclientandserver_8h.html#a5eadd4429627d82193b37536d4faa03a">_LIT</a>(KTxtInvokingProtocol,<span class="stringliteral">"invoking protocol - event 3\n"</span>);
<a name="l00139"></a>00139 console->Printf(KTxtInvokingProtocol);
<a name="l00140"></a>00140 <span class="comment">// Handle an event</span>
<a name="l00141"></a>00141 aProtocol->HandleEvent(3);
<a name="l00142"></a>00142 }
<a name="l00143"></a>00143
<a name="l00144"></a>00144
<a name="l00146"></a>00146 <span class="comment">//</span>
<a name="l00147"></a>00147 <span class="comment">// -----> CProtocolProvider (implementation)</span>
<a name="l00148"></a>00148 <span class="comment">//</span>
<a name="l00150"></a>00150 <span class="comment"></span>CProtocolProvider* CProtocolProvider::NewLC()
<a name="l00151"></a>00151 {
<a name="l00152"></a>00152 CProtocolProvider* <span class="keyword">self</span>=<span class="keyword">new</span>(ELeave) CProtocolProvider;
<a name="l00153"></a>00153 CleanupStack::PushL(<span class="keyword">self</span>);
<a name="l00154"></a>00154 <span class="keyword">self</span>->ConstructL();
<a name="l00155"></a>00155 <span class="keywordflow">return</span> <span class="keyword">self</span>;
<a name="l00156"></a>00156 };
<a name="l00157"></a>00157
<a name="l00158"></a>00158 CProtocolProvider::~CProtocolProvider()
<a name="l00159"></a>00159 {
<a name="l00160"></a>00160 <span class="keyword">delete</span> iProtocolUser;
<a name="l00161"></a>00161 }
<a name="l00162"></a>00162
<a name="l00163"></a>00163 <span class="keywordtype">void</span> CProtocolProvider::ConstructL()
<a name="l00164"></a>00164 {
<a name="l00165"></a>00165 iProtocolUser=CProtocolUser::NewL();
<a name="l00166"></a>00166 }
<a name="l00167"></a>00167
<a name="l00168"></a>00168 <span class="keywordtype">void</span> CProtocolProvider::CallProtocolUser()
<a name="l00169"></a>00169 {
<a name="l00170"></a>00170 <span class="comment">// Call the protocol user to do some work</span>
<a name="l00171"></a>00171 <a class="code" href="secureclientandserver_8h.html#a5eadd4429627d82193b37536d4faa03a">_LIT</a>(KTxtCallProtUser,<span class="stringliteral">"CProtocolProvider calling protocol user\n"</span>);
<a name="l00172"></a>00172 console->Printf(KTxtCallProtUser);
<a name="l00173"></a>00173 iProtocolUser->DoSomething(<span class="keyword">this</span>);
<a name="l00174"></a>00174 <span class="comment">// pass ourselves, disguised as our mixin</span>
<a name="l00175"></a>00175 <span class="comment">// protocol base, to the protocol user</span>
<a name="l00176"></a>00176 }
<a name="l00177"></a>00177
<a name="l00178"></a>00178 <span class="keywordtype">void</span> CProtocolProvider::HandleEvent(TInt aEventCode)
<a name="l00179"></a>00179 {
<a name="l00180"></a>00180 <span class="comment">// A concrete implementation of the abstract protocol.</span>
<a name="l00181"></a>00181 <span class="comment">// Handle an event in the protocol user</span>
<a name="l00182"></a>00182 <a class="code" href="secureclientandserver_8h.html#a5eadd4429627d82193b37536d4faa03a">_LIT</a>(KFormat1,<span class="stringliteral">"CProtocolProvider handling event %d\n"</span>);
<a name="l00183"></a>00183 console->Printf(KFormat1,aEventCode);
<a name="l00184"></a>00184 }
<a name="l00185"></a>00185
<a name="l00186"></a>00186
<a name="l00188"></a>00188 <span class="comment">//</span>
<a name="l00189"></a>00189 <span class="comment">// Do the example</span>
<a name="l00190"></a>00190 <span class="comment">//</span>
<a name="l00192"></a>00192 <span class="comment"></span>LOCAL_C <span class="keywordtype">void</span> doExampleL()
<a name="l00193"></a>00193 {
<a name="l00194"></a>00194 <span class="comment">// show use of mixin with simple class</span>
<a name="l00195"></a>00195 CProtocolProvider* simpleProvider=CProtocolProvider::NewLC();
<a name="l00196"></a>00196 <span class="comment">// call protocol user</span>
<a name="l00197"></a>00197 simpleProvider->CallProtocolUser();
<a name="l00198"></a>00198 <span class="comment">// Remove simpleProvider from cleanup stack and destroy</span>
<a name="l00199"></a>00199 CleanupStack::PopAndDestroy();
<a name="l00200"></a>00200 }
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