TB10.1 Example Applications: examples/Basics/MClasses3/MClasses3.cpp Source File

00001 // Copyright (c) 1997-2009 Nokia Corporation and/or its subsidiary(-ies).
-00002 // All rights reserved.
-00003 // This component and the accompanying materials are made available
-00004 // under the terms of "Eclipse Public License v1.0"
-00005 // which accompanies this distribution, and is available
-00006 // at the URL "http://www.eclipse.org/legal/epl-v10.html".
-00007 //
-00008 // Initial Contributors:
-00009 // Nokia Corporation - initial contribution.
-00010 //
-00011 // Contributors:
-00012 //
-00013 // Description:
-00014 // Demonstrate use of M classes, or mixins - the
-00015 // only use of multiple inheritance that has been
-00016 // sanctioned by the E32 architecture team
-00017 // This example shows how mixins can be used to
-00018 // pass some protocol, and an associated object, from
-00019 // a protocol provider to an protocol user.  The user
-00020 // is not supposed to know everything about the provider,
-00021 // only about the protocol it's interested in.
-00022 // In this specific example, the provider is derived from
-00023 // an appropriate base class, and a mixin class representing
-00024 // the protocol. The benefits of the method shown in example EUTYPEM2
-00025 // are  thus gained, without the inconvenience of intermediary
-00026 // classes.
-00027 //
-00028 
-00029 
-00030 
-00031 #include "CommonFramework.h"
-00032 
-00034 //
-00035 // -----> CProtocol (definition)
-00036 //
-00037 // A protocol class for mixing in
-00038 //
-00040 class MProtocol
-00041         {
-00042 public:
-00043         virtual void HandleEvent(TInt aEventCode)=0;
-00044         };
-00045 
-00046 
-00048 //
-00049 // -----> CProtocolUser (definition)
-00050 //
-00051 // Define a protocol user which uses this protocol
-00052 //
-00054 class CProtocolUser : public CBase
-00055         {
-00056 public:
-00057           // Construction
-00058         static CProtocolUser* NewLC();
-00059         static CProtocolUser* NewL();
-00060 
-00061           // Destruction
-00062         ~CProtocolUser();
-00063 
-00064           // Some function which uses a protocol
-00065         void DoSomething(MProtocol* aProtocol);
-00066 
-00067 protected:
-00068           // Construction assistance
-00069         void ConstructL();
-00070         };
-00071 
-00072 
-00074 //
-00075 // -----> CProtocolProvider (definition)
-00076 //
-00077 // A simple class which uses the mixin
-00078 //
-00080 class CProtocolProvider : public CBase, public MProtocol
-00081         {
-00082 public:
-00083           // Construction
-00084         static CProtocolProvider* NewLC();
-00085 
-00086           // Destruction
-00087         ~CProtocolProvider();
-00088 
-00089           // Calls the protocol user
-00090         void CallProtocolUser();
-00091 
-00092           // Implement the protocol (handles the protocol)
-00093         void HandleEvent(TInt aEventCode);
-00094 
-00095 protected:
-00096           // Construction assistance
-00097         void ConstructL();
-00098 
-00099 private:
-00100           // data members defined by this class
-00101         CProtocolUser*     iProtocolUser;
-00102         };
-00103 
-00104 
-00106 //
-00107 // -----> CProtocolUser (implementation)
-00108 //
-00110 CProtocolUser* CProtocolUser::NewLC()
-00111         {
-00112         CProtocolUser* self=new(ELeave) CProtocolUser;
-00113         CleanupStack::PushL(self);
-00114         self->ConstructL();
-00115         return self;
-00116         }
-00117 
-00118 CProtocolUser* CProtocolUser::NewL()
-00119         {
-00120         CProtocolUser* self=NewLC();
-00121         CleanupStack::Pop();
-00122         return self;
-00123         }
-00124 
-00125 CProtocolUser::~CProtocolUser()
-00126         {
-00127         }
-00128 
-00129 void CProtocolUser::ConstructL()
-00130         {
-00131         }
-00132 
-00133 void CProtocolUser::DoSomething(MProtocol* aProtocol)
-00134         {
-00135           // Do something that requires a protocol
-00136         _LIT(KTxtExtSystemDoing,"External system doing something\n");
-00137         console->Printf(KTxtExtSystemDoing);
-00138         _LIT(KTxtInvokingProtocol,"invoking protocol - event 3\n");
-00139         console->Printf(KTxtInvokingProtocol);
-00140           // Handle an event
-00141         aProtocol->HandleEvent(3);
-00142         }
-00143 
-00144 
-00146 //
-00147 // -----> CProtocolProvider (implementation)
-00148 //
-00150 CProtocolProvider* CProtocolProvider::NewLC()
-00151         {
-00152         CProtocolProvider* self=new(ELeave) CProtocolProvider;
-00153         CleanupStack::PushL(self);
-00154         self->ConstructL();
-00155         return self;
-00156         };
-00157 
-00158 CProtocolProvider::~CProtocolProvider()
-00159         {
-00160         delete iProtocolUser;
-00161         }
-00162 
-00163 void CProtocolProvider::ConstructL()
-00164         {
-00165         iProtocolUser=CProtocolUser::NewL();
-00166         }
-00167 
-00168 void CProtocolProvider::CallProtocolUser()
-00169         { 
-00170           // Call the protocol user to do some work
-00171         _LIT(KTxtCallProtUser,"CProtocolProvider calling protocol user\n");
-00172         console->Printf(KTxtCallProtUser);
-00173         iProtocolUser->DoSomething(this);
-00174          // pass ourselves, disguised as our mixin
-00175          // protocol base, to the protocol user
-00176         }
-00177 
-00178 void CProtocolProvider::HandleEvent(TInt aEventCode)
-00179         { 
-00180           // A concrete implementation of the abstract protocol.
-00181           // Handle an event in the protocol user
-00182         _LIT(KFormat1,"CProtocolProvider handling event %d\n");
-00183         console->Printf(KFormat1,aEventCode);
-00184         }
-00185 
-00186 
-00188 //
-00189 // Do the example
-00190 //
-00192 LOCAL_C void doExampleL()
-00193     {
-00194           // show use of mixin with simple class
-00195         CProtocolProvider* simpleProvider=CProtocolProvider::NewLC();
-00196           // call protocol user
-00197         simpleProvider->CallProtocolUser();
-00198           // Remove simpleProvider from cleanup stack and destroy
-00199         CleanupStack::PopAndDestroy();
-00200         }
-