TB10.1 Example Applications: examples/Base/MemMan/Cleanup/TrapD/TrapD.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 // Example shows creation and use of of an object protected by a TRAPD
+00015 // NOTE: the structure of this example is different to standard E32 examples
+00016 //
+00017 
+00018 
+00019 #include <e32cons.h>
+00020 
+00021   // All messages written to this
+00022 LOCAL_D CConsoleBase* console;
+00023   
+00024   // Flag which determines whether the doSomething() member function
+00025   // of the CExample class should leave when called.
+00026 LOCAL_D TBool leaveFlag = ETrue;
+00027 
+00028   // Parameter for __UHEAP_SETFAIL
+00029   // Allocation guaranteed to fail at this number of allocation attempts;
+00030   // i.e. if set to n, allocation fails on the nth attempt. 
+00031   // NB only used in debug mode
+00032 #ifdef _DEBUG
+00033 LOCAL_D TInt allocFailNumber = 1;
+00034 #endif
+00035   
+00036   // Function prototypes
+00037 LOCAL_C void doExampleL();      
+00038 LOCAL_C void callExampleL();
+00039 
+00040 
+00041 
+00043 //
+00044 // -----> CExample (definition)
+00045 //
+00046 // The class is used by the example code
+00047 //
+00049 class CExample : public CBase
+00050         {
+00051 public :
+00052         void DoSomethingL();
+00053 public :
+00054         TInt iInt;
+00055         };
+00056 
+00057 
+00059 //
+00060 // -----> CExample (implementation)
+00061 //
+00063 void CExample::DoSomethingL() 
+00064         {
+00065           // Leave if the global flag is set
+00066         if (leaveFlag)
+00067                 {
+00068                 _LIT(KMsgLeaving,"DoSomethingL leaving.\n");
+00069                 console->Printf(KMsgLeaving);
+00070                 User::Leave(KErrGeneral);               
+00071                 }
+00072         _LIT(KFormat1,"Value of iInt is %d.\n");
+00073         console->Printf(KFormat1,iInt);
+00074         }
+00075 
+00077 //
+00078 // Main function called by E32
+00079 //
+00081 GLDEF_C TInt E32Main()
+00082     {
+00083           // Get cleanup stack
+00084         CTrapCleanup* cleanup=CTrapCleanup::New();
+00085 
+00086           // Some more initialization, then do the example
+00087         TRAPD(error,callExampleL());
+00088           
+00089           // callExampleL() should never leave.
+00090         _LIT(KMsgPanicEpoc32ex,"EPOC32EX");
+00091         __ASSERT_ALWAYS(!error,User::Panic(KMsgPanicEpoc32ex,error));
+00092 
+00093           // destroy the cleanup stack
+00094         delete cleanup;
+00095         
+00096           // return
+00097         return 0;
+00098     }
+00099 
+00100 
+00102 //
+00103 //
+00104 //
+00106 LOCAL_C void callExampleL() 
+00107     {
+00108           // Initialize and call the example code under cleanup stack.
+00109         _LIT(KMsgExampleCode,"Symbian platform Example Code");
+00110         console = Console::NewL(KMsgExampleCode,TSize(KConsFullScreen,KConsFullScreen));
+00111           // Put console onto the cleanup stack.
+00112         CleanupStack::PushL(console);
+00113 
+00114           // Perform the example function under the protection of a 
+00115           // TRAP harness.
+00116         TRAPD(error,doExampleL());
+00117         _LIT(KMsgOK,"ok");
+00118         _LIT(KFormat2,"failed: leave code = %d");
+00119         if (error)
+00120                 console->Printf(KFormat2,error);
+00121         else
+00122                 console->Printf(KMsgOK);
+00123           
+00124           // Continue
+00125         _LIT(KMsgPressAnyKey," [press any key]");
+00126         console->Printf(KMsgPressAnyKey);
+00127         console->Getch();
+00128 
+00129           // Remove the console object from the cleanupstack
+00130           // and destroy it. 
+00131         CleanupStack::PopAndDestroy();
+00132     }
+00133 
+00134 
+00136 //
+00137 // Do the example
+00138 //
+00139 // Create and use an instance of CExample, protected by TRAPD
+00140 //
+00142 void doExampleL()
+00143         {
+00144           // Memory alloc fails on the 'allocFailNumber' attempt. 
+00145         __UHEAP_SETFAIL(RHeap::EDeterministic,allocFailNumber);
+00146           // Allocate - leave if allocation fails.
+00147         CExample* myExample = new (ELeave) CExample;
+00148           // Do something that cannot leave (no protection needed)
+00149         myExample->iInt = 5;
+00150           // Do something that can leave and trap the failure
+00151         TRAPD(error,myExample->DoSomethingL());
+00152           // Delete the CExample object
+00153         delete myExample;
+00154           // Now check whether DoSomethingL() left
+00155         User::LeaveIfError(error);
+00156         }
+00157 
+00158 
+00159 
+00160 
+00161 
+00162 
+00163 
+00164 
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