passing by reference... my darkest enemy
actual reason below:
In your case (without reference) the compiler generates a temporary object (int) for the first argument of your MyApplication constructor. You pass this temporary int to QApplication’s constructor (with int reference), which saves the address of this reference. Once your MyApplication constructor is done the temporary int is destroyed but QApplication still has its address.
/*
* Hedgewars, a free turn based strategy game
* Copyright (c) 2011 Andrey Korotaev <unC0Rr@gmail.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; version 2 of the License
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#ifndef DRAWMAPSCENE_H
#define DRAWMAPSCENE_H
#include <QGraphicsScene>
#include <QPainterPath>
class QGraphicsPathItem;
typedef QList<QList<QPoint> > Paths;
class DrawMapScene : public QGraphicsScene
{
Q_OBJECT
public:
explicit DrawMapScene(QObject *parent = 0);
QByteArray encode();
void decode(QByteArray data);
signals:
void pathChanged();
public slots:
void undo();
void clearMap();
void simplifyLast();
private:
QPen m_pen;
QBrush m_brush;
QGraphicsPathItem * m_currPath;
Paths paths;
virtual void mouseMoveEvent(QGraphicsSceneMouseEvent * mouseEvent);
virtual void mousePressEvent(QGraphicsSceneMouseEvent * mouseEvent);
virtual void mouseReleaseEvent(QGraphicsSceneMouseEvent * mouseEvent);
QPainterPath pointsToPath(const QList<QPoint> points);
};
#endif // DRAWMAPSCENE_H