Unsolved QStateMachine, detect unhandled signals/ transitions
-
Hello all, I'm using a QStateMachine with qsignaltransitions, which hooks into an existing, large set of signals.
I'd like to be able to notify the user / log an error when the state machine receives a signal which doesn't correspond to a transition for the currently active state- kind of like a fall-through behaviour?
A crude way of handling this would be for each state to have transitions to an error/ warning state for every signal transition it's not interested in- which feels wrong/ impractical.
Any help appreciated.
-
Hi and welcome to devnet,
I would rather go with a subclass of QSignalTransition like show in the class documentation.
-
Thanks for the tip- I'll give that a go!
Cheers -
Still struggling with this- I'm not sure I'm going about it the right way. I have tried subclassing QSignalTransition and overriding eventTest, where I can raise an error if the incoming signal is not handled. The problem is, the transition appears to only receive events that are relevant to it, rather than all signals- so it doesn't provide a single checkpoint against which I can capture an unhandled signal.
Any further tips on how to achieve the original goal? -
Can you provide a minimal compilable example that demonstrate the situation you have ?
-
Hi, thanks for the reply, here's some code to demonstrate the issue. Note, I expected the debug output from the eventTest() routine to get output when the signal fires but it doesn't. If I change the initial state I can get it to work, presumably because this determines which transitions are active.
I believe I could achieve what I want by using a parent state and registering transitions on that, for every signal, but I was hoping there's a more elegant solution?
Thanks"
/****************************************************************************
**
** Copyright (C) 2016 The Qt Company Ltd.
** Contact: https://www.qt.io/licensing/
**
** This file is part of the QtCore module of the Qt Toolkit.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
** * Redistributions of source code must retain the above copyright
** notice, this list of conditions and the following disclaimer.
** * Redistributions in binary form must reproduce the above copyright
** notice, this list of conditions and the following disclaimer in
** the documentation and/or other materials provided with the
** distribution.
** * Neither the name of The Qt Company Ltd nor the names of its
** contributors may be used to endorse or promote products derived
** from this software without specific prior written permission.
**
**
** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
** "AS IS" 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
** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
**
** $QT_END_LICENSE$
**
****************************************************************************/#include <QtCore>
#include <stdio.h>
#include <QStateMachine>
#include <QThread>class QStatePlus: public QState
{
public:
QStatePlus(QString name, QState *parent = 0)
: QState(parent),m_name(name){}
virtual void onEntry(QEvent *event) override {qDebug () << "Entering state " << m_name;}
QElapsedTimer t;
QString m_name;
};class QTransitionPlus : public QSignalTransition
{
public:
template <typename PMF>
QTransitionPlus( const typename QtPrivate::FunctionPointer<PMF>::Object obj, PMF signal, const QString& name)
: QSignalTransition(obj, signal),
m_name(name){}
protected:
bool eventTest(QEvent e) {
if (!QSignalTransition::eventTest(e))
{
if(e->type() == QEvent::StateMachineSignal)
{
QString statename;
QStatePlus qsp = dynamic_cast<QStatePlus>(this->sourceState());
if(qsp)
{
statename = qsp->m_name;
}
qDebug () << "XXX unhandled signal in state: " << statename << " " << "in transition" << m_name;
}
return false;
}
return true;
}
private:
QString m_name;
};class QStateMachinePlus: public QStateMachine
{
Q_OBJECT
public:QStateMachinePlus(QObject *parent = 0) : QStateMachine(parent){}
// virtual bool event(QEvent *e) override {qDebug () << "XXX MACHINE event address " << QState::event(e); qDebug () << "accepted " << e->isAccepted(); return true; }
void emitTest1To2(){qDebug() << "emit 1to2"; emit sig1To2();} void emitTest2To3(){qDebug() << "emit 2to3"; emit sig2To3();} void emitTest3To1(){qDebug() << "emit 3to1"; emit sig3To1();}
signals:
void sig1To2();
void sig2To3();
void sig3To1();
void test();
public slots:
void handlesig2To3(){/qDebug() << "Got handlesig2To3";/}
void handlesig1To2(){/qDebug() << "Got handlesig1To2";/}
};//! [3]
int main(int argc, char argv)
{
QTimer t1;
QTimer t2;
QCoreApplication app(argc, argv);
QStateMachinePlus machine;
QStatePlus s1 = new QStatePlus("s1");
QStatePlus s2 = new QStatePlus("s2");
QStatePlus* s3 = new QStatePlus("s3");
machine.addState(s1);
machine.addState(s2);
machine.addState(s3);machine.setInitialState(s2); QTransitionPlus* trans1To2 = new QTransitionPlus(&machine, &QStateMachinePlus::sig1To2, "1 to 2"); trans1To2->setTargetState(s2); QTransitionPlus* trans2To3 = new QTransitionPlus(&machine, &QStateMachinePlus::sig2To3, "2 to 3"); trans2To3->setTargetState(s3); QTransitionPlus* trans3To1 = new QTransitionPlus(&machine, &QStateMachinePlus::sig3To1, "3 to 1"); trans3To1 ->setTargetState(s1); s1->addTransition(trans1To2); s2->addTransition(trans2To3); s3->addTransition(trans3To1); machine.start(); qDebug() <<"Start test"; t1.setInterval(5000); QObject::connect(&t1, &QTimer::timeout, &machine, &QStateMachinePlus::emitTest1To2); //t1.setSingleShot(true); t1.start();
// t2.setInterval(1000);
// t2.setSingleShot(true);
// QObject::connect(&t2, &QTimer::timeout, &machine, &QStateMachinePlus::emitTest1To2);
// t2.start();return app.exec();
}
//! [6]#include "main.moc"
"