Suggestions on how to make an alarmclock-like function

[Tottish]

I think you're right, it sounds more convenient too. I'm back at the computer now so I'll get right on it!
Cheers!
/Tottish

[Tottish]

So after some time I got it to work.

I spent quite a bit of time trying to get the iterator in addAlarm to cooperate but I never quite got the hang of it so I did it in a way that seemed more familiar to me. Please let me know if my way is less suitable or if I misunderstood the purpose of the iterator.

I also spent some time scratching my head before I realized why the program crashed if the alarm list goes empty. But it seems that that's what happens if one tries to read from list.first in an empty list so I built in protection for that too. Other than that it's pretty much the same as what wysota posted above.

Should anyone else be building an alarm clock or timer of some sort, here is my version (I'm not guaranteeing anything but it seems pretty stable):

#ifndef REPORTTIMER_H
#define REPORTTIMER_H
 
#include <QtCore>
 
class ReportTimer : public QObject {
    Q_OBJECT
 
public:
    ReportTimer(QObject *parent = 0) : QObject(parent), m_timer(0) {}
public slots:
  void start() {
    if(m_timer!=0) return;
    m_timer = startTimer(4000); // 4s resolution
  }
 
  void stop() {
    if(m_timer==0) return;
    killTimer(m_timer);
    m_timer = 0;
  }
 
  void addAlarm(const QDateTime &dt) {
      qDebug() << "in";
      if (m_alarms.indexOf(dt) != -1) return; //if already in list, return
      else {m_alarms.append(dt); qSort(m_alarms);}
  }
 
signals:
  void alarm(const QDateTime &dt);
 
protected:
  void timerEvent(QTimerEvent *ev) { qDebug() << "Fired" << m_alarms;
    if(ev->timerId()!=m_timer) { QObject::timerEvent(ev); return; }
    QDateTime current = QDateTime::currentDateTime();
    while(m_alarms.isEmpty() == false && m_alarms.first() <= current) {
        emit alarm(m_alarms.first());
        m_alarms.removeFirst();
    }
}
 
 
private:
  QList<QDateTime> m_alarms;
  int m_timer;
};
 
#endif // REPORTTIMER_H

#ifndef REPORTTIMER_H
#define REPORTTIMER_H

#include <QtCore>

class ReportTimer : public QObject {
    Q_OBJECT

public:
    ReportTimer(QObject *parent = 0) : QObject(parent), m_timer(0) {}
public slots:
  void start() {
    if(m_timer!=0) return;
    m_timer = startTimer(4000); // 4s resolution
  }

  void stop() {
    if(m_timer==0) return;
    killTimer(m_timer);
    m_timer = 0;
  }

  void addAlarm(const QDateTime &dt) {
      qDebug() << "in";
      if (m_alarms.indexOf(dt) != -1) return; //if already in list, return
      else {m_alarms.append(dt); qSort(m_alarms);}
  }

signals:
  void alarm(const QDateTime &dt);

protected:
  void timerEvent(QTimerEvent *ev) { qDebug() << "Fired" << m_alarms;
    if(ev->timerId()!=m_timer) { QObject::timerEvent(ev); return; }
    QDateTime current = QDateTime::currentDateTime();
    while(m_alarms.isEmpty() == false && m_alarms.first() <= current) {
        emit alarm(m_alarms.first());
        m_alarms.removeFirst();
    }
}


private:
  QList<QDateTime> m_alarms;
  int m_timer;
};

#endif // REPORTTIMER_H

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Cheers!
/Tottish

[wysota]

I don't get why you replaced what I had with your line #26. It's suboptimal. The code just had two typos After correcting them it compiles and works fine. Here is the corrected code:

#include <QtGui>
#include <QObject>
 
class AlarmClock : public QObject {
    Q_OBJECT
public:
  AlarmClock(QObject *parent = 0) : QObject(parent), m_timer(0) {}
public slots:
  void start(int ms = 1000) {
    if(m_timer!=0) return;
    m_timer = startTimer(ms); // 1s resolution
  }
  void stop() {
    if(m_timer==0) return;
    killTimer(m_timer);
    m_timer = 0;
  }
  void addAlarm(const QDateTime &dt) {
    QList<QDateTime>::iterator iter = qLowerBound(m_alarms.begin(), m_alarms.end(), dt);
    if(iter==m_alarms.end() || *iter != dt) m_alarms.insert(iter, dt);
  }
signals:
  void alarm(const QDateTime &dt);
protected:
  void timerEvent(QTimerEvent *ev) {
    if(ev->timerId()!=m_timer) { QObject::timerEvent(ev); return; }
    QDateTime current = QDateTime::currentDateTime();
    while(!m_alarms.isEmpty() && m_alarms.first()<=current) {
        emit alarm(m_alarms.first());
        m_alarms.removeFirst();
    }
  }
private:
  QList<QDateTime> m_alarms;
  int m_timer;
};
 
class Dummy : public QObject {
    Q_OBJECT
public slots:
    void onAlarm(const QDateTime &dt) {
	qDebug() << dt;
    }
};
 
#include "main.moc"
 
int main(int argc, char **argv){
    QApplication app(argc, argv);
    AlarmClock alarms;
    Dummy d;
    d.connect(&alarms, SIGNAL(alarm(QDateTime)), &d, SLOT(onAlarm(QDateTime)));
    alarms.addAlarm(QDateTime(QDate::currentDate(), QTime::currentTime().addSecs(2)));
    alarms.addAlarm(QDateTime(QDate::currentDate(), QTime::currentTime().addSecs(6)));
    alarms.addAlarm(QDateTime(QDate::currentDate(), QTime::currentTime().addSecs(14)));
    alarms.addAlarm(QDateTime(QDate::currentDate(), QTime::currentTime().addSecs(10)));
    alarms.start();
    return app.exec();
}

#include <QtGui>
#include <QObject>

class AlarmClock : public QObject {
    Q_OBJECT
public:
  AlarmClock(QObject *parent = 0) : QObject(parent), m_timer(0) {}
public slots:
  void start(int ms = 1000) {
    if(m_timer!=0) return;
    m_timer = startTimer(ms); // 1s resolution
  }
  void stop() {
    if(m_timer==0) return;
    killTimer(m_timer);
    m_timer = 0;
  }
  void addAlarm(const QDateTime &dt) {
    QList<QDateTime>::iterator iter = qLowerBound(m_alarms.begin(), m_alarms.end(), dt);
    if(iter==m_alarms.end() || *iter != dt) m_alarms.insert(iter, dt);
  }
signals:
  void alarm(const QDateTime &dt);
protected:
  void timerEvent(QTimerEvent *ev) {
    if(ev->timerId()!=m_timer) { QObject::timerEvent(ev); return; }
    QDateTime current = QDateTime::currentDateTime();
    while(!m_alarms.isEmpty() && m_alarms.first()<=current) {
        emit alarm(m_alarms.first());
        m_alarms.removeFirst();
    }
  }
private:
  QList<QDateTime> m_alarms;
  int m_timer;
};

class Dummy : public QObject {
    Q_OBJECT
public slots:
    void onAlarm(const QDateTime &dt) {
	qDebug() << dt;
    }
};

#include "main.moc"

int main(int argc, char **argv){
    QApplication app(argc, argv);
    AlarmClock alarms;
    Dummy d;
    d.connect(&alarms, SIGNAL(alarm(QDateTime)), &d, SLOT(onAlarm(QDateTime)));
    alarms.addAlarm(QDateTime(QDate::currentDate(), QTime::currentTime().addSecs(2)));
    alarms.addAlarm(QDateTime(QDate::currentDate(), QTime::currentTime().addSecs(6)));
    alarms.addAlarm(QDateTime(QDate::currentDate(), QTime::currentTime().addSecs(14)));
    alarms.addAlarm(QDateTime(QDate::currentDate(), QTime::currentTime().addSecs(10)));
    alarms.start();
    return app.exec();
}

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[Tottish]

Well, as I said, I changed it to a syntax that I felt more familiar with since I couldn't get the iterator to work/finding and correcting the "typo" =).
"Suboptimal", I'm assuming you mean that the functionality/behavior is the same but your iterator way is faster? I'll take your word for it. *Changing code*
In any case it was nice to find a solution on my own. Suboptimal as it may be. =)
Thanks wysota!
Have an awesome day!
/Tottish

[wysota]

The difference is you are resorting the list when adding a new element while in fact the list is already sorted with exception of one element. My solution just looks for the proper place to insert the element in an already sorted array so it's faster. The use of iterators is irrelevant here, they are there only because there is no qLowerBound() version that returns an index.

[Tottish]

OK, I see. Thank you for the clarification!
/Tottish