examples/Base/MemMan/Cleanup/ErrorOnFail/ErrorOnFail.cpp

/*
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  may be used to endorse or promote products derived from this software
  without specific prior written permission.

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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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Description: 
Example shows attempt to construct an object and return an
appropriate error code on failure.
NOTE: the structure of this example is different to standard E32 examples 
*/




#include <e32cons.h>


//
// Common formats
//


_LIT(KCommonFormat1,"Value of iInt is %d.\n");


  // All messages written to this
LOCAL_D CConsoleBase* console;
  
  // Flag which determines whether the doSomething() member function
  // of the CExample class should leave when called.
LOCAL_D TBool leaveFlag = ETrue;

  // Parameter for __UHEAP_SETFAIL
  // Allocation guaranteed to fail at this number of allocation attempts;
  // i.e. if set to n, allocation fails on the nth attempt. 
  // NB only used in debug mode
#ifdef _DEBUG
LOCAL_D TInt allocFailNumber = 1;
#endif
  
  // Function prototypes
LOCAL_C TInt doExample();      
LOCAL_C void callExampleL();



//
// -----> CExample (definition)
//
// The class is used by the example code
//
class CExample : public CBase
        {
public :
        void DoSomethingL();
public :
        TInt iInt;
        };


//
// -----> CExample (implementation)
//
void CExample::DoSomethingL() 
        {
          // Leave if the global flag is set
        if (leaveFlag)
                {
                _LIT(KMsgLeaving,"DoSomethingL leaving.\n");
                console->Printf(KMsgLeaving);
                User::Leave(KErrGeneral);               
                }
        console->Printf(KCommonFormat1,iInt);
        }

//
// Main function called by E32
//
GLDEF_C TInt E32Main()
    {
          // Get cleanup stack
        CTrapCleanup* cleanup=CTrapCleanup::New();

          // Some more initialization, then do the example
        TRAPD(error,callExampleL());
          
          // callExampleL() should never leave.
        _LIT(KMsgPanicEpoc32ex,"EPOC32EX");
        __ASSERT_ALWAYS(!error,User::Panic(KMsgPanicEpoc32ex,error));

          // destroy the cleanup stack
        delete cleanup;
        
          // return
        return 0;
    }


//
//
//
LOCAL_C void callExampleL() 
    {
          // Initialize and call the example code under cleanup stack
        _LIT(KMsgExampleCode,"Symbian platform Example Code");
        console = Console::NewL(KMsgExampleCode,TSize(KConsFullScreen,KConsFullScreen));
          // Put console onto the cleanup stack
        CleanupStack::PushL(console);

          // Perform the example function
        TInt retVal;
        retVal = doExample();

          // Show the value returned from the example
        _LIT(KFormat2,"Return code=%d.\n");
        console->Printf(KFormat2, retVal);
        _LIT(KMsgPressAnyKey," [press any key]");
        console->Printf(KMsgPressAnyKey);
        console->Getch();

          // Remove the console object from the cleanupstack
          // and destroy it 
        CleanupStack::PopAndDestroy();
    }


//
// Do the example
//
TInt doExample()
        {
          // Memory alloc fails on the 'allocFailNumber' attempt.
        __UHEAP_SETFAIL(RHeap::EDeterministic,allocFailNumber);
          // Allocate and test
        CExample* myExample = new CExample;
        if (!myExample) return(KErrNoMemory); 
          // Do something with the CExample object
        myExample->iInt = 5;
          //
        console->Printf(KCommonFormat1,myExample->iInt);
          // Delete the CExample object
        delete myExample;
          // Completed OK
        return KErrNone;
        }

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