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Thread: Timer not connecting to private SLOT

  1. #1
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    Default Timer not connecting to private SLOT

    This is my header:
    Qt Code:
    1. #ifndef ALARMH_H
    2. #define ALARMH_H
    3.  
    4. class Alarm : public QObject
    5. {
    6. Q_OBJECT
    7.  
    8. public:
    9. Alarm(QString file)
    10. {
    11. // code here
    12. }
    13. int parseXML(QDomDocument doc, QString file)
    14. {
    15. // code here
    16. }
    17. void checkAlarm()
    18. {
    19. QTimer *timer = new QTimer(this);
    20. connect(timer, SIGNAL(timeout()), this, SLOT(checkTime()));
    21. qDebug() << timer->timerId();
    22. timer->start(100);
    23. }
    24. private:
    25. QString alarmName;
    26. QTime alarmTime;
    27. QDate alarmDate;
    28. QString alarmSound;
    29. QString alarmMessage;
    30. QString alarmApp;
    31. QString alarmAppArg;
    32.  
    33. signals:
    34. void soundAlarm();
    35.  
    36. private slots:
    37. void checkTime()
    38. {
    39. qDebug() << "check ....";
    40. }
    41.  
    42.  
    43. };
    44. #endif // ALARMH_H
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    I use it in .cpp:
    Qt Code:
    1. Alarm a(filename);
    2. a.checkAlarm();
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    But the timer somehow does not call the SLOT once it's timed out. Probably my mistake, but where?

  2. #2
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    Default Re: Timer not connecting to private SLOT

    Please create your timer variable class level. So now your header will be:
    Qt Code:
    1. #ifndef ALARMH_H
    2. #define ALARMH_H
    3.  
    4. class Alarm : public QObject
    5. {
    6. Q_OBJECT
    7. QTimer *timer;
    8. public:
    9. Alarm(QString file)
    10. {
    11. // code here
    12. }
    13. int parseXML(QDomDocument doc, QString file)
    14. {
    15. // code here
    16. }
    17. void checkAlarm()
    18. {
    19. timer = new QTimer(this);
    20. if(!connect(timer, SIGNAL(timeout()), this, SLOT(checkTime()))
    21. {
    22. qDebug()<<"Critical!! Cannot connect";
    23. }
    24.  
    25. qDebug() << timer->timerId();
    26. timer->start(100);
    27. }
    28. private:
    29. QString alarmName;
    30. QTime alarmTime;
    31. QDate alarmDate;
    32. QString alarmSound;
    33. QString alarmMessage;
    34. QString alarmApp;
    35. QString alarmAppArg;
    36.  
    37. signals:
    38. void soundAlarm();
    39.  
    40. private slots:
    41. void checkTime()
    42. {
    43. qDebug() << "check ....";
    44. }
    45.  
    46.  
    47. };
    48. #endif // ALARMH_H
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  3. #3
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    Default Re: Timer not connecting to private SLOT

    Still no sign of the SLOT being called.

  4. #4
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    Default Re: Timer not connecting to private SLOT

    You are creating your object on the stack. If it's inside some scope, like a function or method other than main, it will go out of scope and be destroyed.
    Your biological and technological distinctiveness will be added to our own. Resistance is futile.

    Please ask Qt related questions on the forum and not using private messages or visitor messages.


  5. #5
    Join Date
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    Default Re: Timer not connecting to private SLOT

    Ok, I finnaly understand the whole heap/stack stuff now. Thanks wysota.
    It's working now.
    Off topic:
    What do you think about the Class? Will having , let's say, 20 new Alarm classes affect the programs usage of computers rescources to much?

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