examples/Base/IPC/pubsub/subscribepe.cpp

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// Copyright (c) 2008-2009 Nokia Corporation and/or its subsidiary(-ies).
// All rights reserved.
// This component and the accompanying materials are made available
// under the terms of "Eclipse Public License v1.0"
// which accompanies this distribution, and is available
// at the URL "http://www.eclipse.org/legal/epl-v10.html".
//
// Initial Contributors:
// Nokia Corporation - initial contribution.
//
// Contributors:
//
// Description:
// Demonstrates the pure event pattern of subscribing to an integer property
//



#include "subscribepe.h"

LOCAL_D CConsoleBase* console;

CIntPropertyWatch::CIntPropertyWatch():CActive(EPriority)
        {
        }

void CIntPropertyWatch::ConstructL(CConsoleBase* aConsole)
        {
        User::LeaveIfError(iProperty.Attach(KMyPropertyCat,KMyPropertyName));
        iConsole = aConsole;
        CActiveScheduler::Add(this);
        }

CIntPropertyWatch* CIntPropertyWatch::NewL(CConsoleBase* aConsole)
        {
        CIntPropertyWatch* self = new (ELeave) CIntPropertyWatch;
        CleanupStack::PushL(self);
        self->ConstructL(aConsole);
        CleanupStack::Pop(self);
        return self;
        }

CIntPropertyWatch::~CIntPropertyWatch()
        {
        iProperty.Close();
        Cancel();
        }

void CIntPropertyWatch::DoCancel()
        {
        iProperty.Cancel();
        }

void CIntPropertyWatch::RunL()
        {
        // Receive a notification when a value is published
        // The RProperty::Get() function call can be omitted as the published value is of no importance in the pure event pattern
        TInt value;
        TInt err = iProperty.Get(value);
        if (err == KErrNotFound)
                {
                // No need to re-subscribe to the property as it has been deleted by the publisher
                CActiveScheduler::Stop();
                }
        else if (err == KErrNone)
                {
                // Print the value of the property
                PrintProperty(value);
                // Re-subscribe to the property
                IssueRequest();
                }
        else
                {
                // Leave the function in case of any other error
                CActiveScheduler::Stop();
                User::Leave(err);
                }
        }

void CIntPropertyWatch::PrintProperty(TInt aValue)
        {
        iConsole->Printf(KTxtValChange,aValue);
        }

void CIntPropertyWatch::WatchL()
        {
        TInt value;
        // Checks if the property exists
        TInt res = iProperty.Get(value);
        if (res == KErrNotFound)
                {
                // Property not defined
                User::Leave(res);
                }
        // Prints the value of the property
        // This is only to illustrate that the value of the property is set by the publisher
        // This value has no significance as the pure event distribution pattern of publish and subscribe is being followed
        PrintProperty(value);
        IssueRequest();
        }

void CIntPropertyWatch::IssueRequest()
        {
        iProperty.Subscribe(iStatus);
        SetActive();
        }

void DoExampleL()
        {
        CActiveScheduler* scheduler = new (ELeave) CActiveScheduler();
        CleanupStack::PushL(scheduler);
        CActiveScheduler::Install(scheduler);

        console->Printf(KTxtPESub);

        // Create the integer property watch active object
        CIntPropertyWatch* obj = CIntPropertyWatch::NewL(console);
        CleanupStack::PushL(obj);

        // Subscribe to the property and start the scheduler
        obj->WatchL();
        CActiveScheduler::Start();

        CleanupStack::PopAndDestroy(obj);
        CleanupStack::PopAndDestroy(scheduler);
        }

GLDEF_C TInt E32Main()
        {
        __UHEAP_MARK;
        CTrapCleanup* cleanup = CTrapCleanup::New();

        TRAPD(createError, console = Console::NewL(KTextConsoleTitle, TSize(KConsFullScreen,KConsFullScreen)));
        if (createError)
                return createError;

        TRAPD(mainError, DoExampleL());
        if (mainError)
                console->Printf(KTextFailed, mainError);
        console->Printf(KTextPressAnyKey);
        console->Getch();

        delete console;
        delete cleanup;
        __UHEAP_MARKEND;
        return KErrNone;
        }

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