TB10.1 Example Applications: examples/Basics/MClasses1/MClasses1.cpp Source File

00001 // Copyright (c) 2000-2009 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 
-00023 // from a CProtocol class.
-00024 //
-00025 
-00026 
-00027 
-00028 #include "CommonFramework.h"
-00029 
-00031 //
-00032 // -----> CProtocol (definition)
-00033 //
-00034 // A protocol class for mixing in
-00035 //
-00037 class CProtocol : public CBase
-00038         {
-00039 public:
-00040         virtual void HandleEvent(TInt aEventCode)=0;
-00041         };
-00042 
-00043 
-00045 //
-00046 // -----> CProtocolUser (definition)
-00047 //
-00048 // Define a protocol user which uses this protocol
-00049 //
-00051 class CProtocolUser : public CBase
-00052         {
-00053 public:
-00054           // Construction
-00055         static CProtocolUser* NewLC();
-00056         static CProtocolUser* NewL();
-00057 
-00058           // Destruction
-00059         ~CProtocolUser();
-00060 
-00061           // Some function which uses a protocol
-00062         void DoSomething(CProtocol* aProtocol);
-00063 
-00064 protected:
-00065           // Construction assistance
-00066         void ConstructL();
-00067         };
-00068 
-00069 
-00071 //
-00072 // -----> CProtocolProvider (definition)
-00073 //
-00074 // A simple class which uses the mixin
-00075 //
-00077 class CProtocolProvider : public CProtocol
-00078         {
-00079 public:
-00080           // Construction
-00081         static CProtocolProvider* NewLC();
-00082 
-00083           // Destruction
-00084         ~CProtocolProvider();
-00085 
-00086           // Calls the protocol user
-00087         void CallProtocolUser();
-00088 
-00089           // Implement the protocol (handles the protocol)
-00090         void HandleEvent(TInt aEventCode);
-00091 
-00092 protected:
-00093           // Construction assistance
-00094         void ConstructL();
-00095 
-00096 private:
-00097           // data member defined by this class
-00098         CProtocolUser* iProtocolUser;
-00099         };
-00100 
-00101 
-00103 //
-00104 // -----> CProtocolUser (implementation)
-00105 //
-00107 CProtocolUser* CProtocolUser::NewLC()
-00108         {
-00109         CProtocolUser* self=new(ELeave) CProtocolUser;
-00110         CleanupStack::PushL(self);
-00111         self->ConstructL();
-00112         return self;
-00113         }
-00114 
-00115 CProtocolUser* CProtocolUser::NewL()
-00116         {
-00117         CProtocolUser* self=NewLC();
-00118         CleanupStack::Pop();
-00119         return self;
-00120         }
-00121 
-00122 CProtocolUser::~CProtocolUser()
-00123         {
-00124         }
-00125 
-00126 void CProtocolUser::ConstructL()
-00127         {
-00128         }
-00129 
-00130 void CProtocolUser::DoSomething(CProtocol* aProtocol)
-00131         {
-00132           // Do something that requires a protocol
-00133         _LIT(KTxtExtSystemDoing,"External system doing something\n");
-00134         console->Printf(KTxtExtSystemDoing);
-00135         _LIT(KTxtInvokingProtocol,"invoking protocol - event 3\n");
-00136         console->Printf(KTxtInvokingProtocol);
-00137           // Handle an event
-00138         aProtocol->HandleEvent(3);
-00139         }
-00140 
-00141 
-00143 //
-00144 // -----> CProtocolProvider (implementation)
-00145 //
-00147 CProtocolProvider* CProtocolProvider::NewLC()
-00148         {
-00149         CProtocolProvider* self=new(ELeave) CProtocolProvider;
-00150         CleanupStack::PushL(self);
-00151         self->ConstructL();
-00152         return self;
-00153         };
-00154 
-00155 CProtocolProvider::~CProtocolProvider()
-00156         {
-00157         delete iProtocolUser;
-00158         }
-00159 
-00160 void CProtocolProvider::ConstructL()
-00161         {
-00162         iProtocolUser=CProtocolUser::NewL();
-00163         }
-00164 
-00165 void CProtocolProvider::CallProtocolUser()
-00166         { 
-00167           // Call the protocol user to do some work
-00168         _LIT(KTxtCallProtUser,"CProtocolProvider calling protocol user\n");
-00169         console->Printf(KTxtCallProtUser);
-00170         iProtocolUser->DoSomething(this);
-00171 
-00172                         // pass ourselves, disguised as our (unique)
-00173                         // base class, so the protocol can be called
-00174                         // back by the protocol user
-00175         }
-00176 
-00177 void CProtocolProvider::HandleEvent(TInt aEventCode)
-00178         { 
-00179           // A concrete implementation of the abstract protocol.
-00180           // Handle an event in the protocol user
-00181         _LIT(KFormat1,"CProtocolProvider handling event %d\n");
-00182         console->Printf(KFormat1,aEventCode);
-00183         }
-00184 
-00185 
-00187 //
-00188 // Do the example
-00189 //
-00191 LOCAL_C void doExampleL()
-00192     {
-00193           // show use of mixin with simple class
-00194         CProtocolProvider* simpleProvider=CProtocolProvider::NewLC();
-00195           // call protocol user
-00196         simpleProvider->CallProtocolUser();
-00197           // Remove simpleProvider from cleanup stack and destroy
-00198         CleanupStack::PopAndDestroy();
-00199         }
-