Direct connection in QML

[wysota]

You have to implement your own element, say DirectConnections.

[mfojtak]

OK, let say I have implemented my DirectConnections object. Now I also have object called Sender which emits signal called signal. And I have object called Receiver with slot called slot(). All three objects are exposed by my QML plugin called CustomPlugin.
The QML would look like this:

import CustomPlugin 1.0
Sender {
   id: sender
}
Receiver {
   id: receiver
}
DirectConnections {
   target: receiver
   NOW HOW DO I CREATE CONNECTION BETWEEN onSignal and receiver.slot()   
}

import CustomPlugin 1.0
Sender {
   id: sender
}
Receiver {
   id: receiver
}
DirectConnections {
   target: receiver
   NOW HOW DO I CREATE CONNECTION BETWEEN onSignal and receiver.slot()   
}

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The question is hidden in the code above. What shloud I do to implement such a class which would understand this: onSignal: receiver.slot() ?
I know you can do it with Connections object. But this object is part of QML language which parses "signal: slot" notation in a special way.
It would be brilliant if I could have custom object which keeps the same notation as Connection object. But how to implement it. Could you provide few lines of code which would illustrate it?

[wysota]

For example:

DirectConnections {
  source: sender.signal
  target: receiver.slot
}

DirectConnections {
  source: sender.signal
  target: receiver.slot
}

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I'm not sure how to access the signal and the slot itself from the C++ side. If you can't find a way to do it, you can always use separate properties for the signal and slot signatures (as strings) that you will then use in the backend.

[anda_skoa]

More likely having two properties of type QObject* and two properties of type QString.
Once all four properties are set, code is triggered that does
1) lookup of slot and signal through QMetaObject
2) call connect with the two objects and the retrieved signal and slot signatures

Cheers,
_

---

Added after 8 minutes:

Ok, I have to say I don't understand the problem.

I get DirectConnection behavior in a simple test application

#ifndef TIMER_H
#define TIMER_H
 
#include <QObject>
 
#include <QtQuick>
 
class QTimer;
 
class Timer : public QObject
{
    Q_OBJECT
 
public:
    explicit Timer( QObject* parent = 0 );
 
signals:
    void timeout();
 
private:
    QTimer* m_timer;
 
private slots:
    void onInternalTimeout();
};
 
#endif // TIMER_H

#ifndef TIMER_H
#define TIMER_H

#include <QObject>

#include <QtQuick>

class QTimer;

class Timer : public QObject
{
    Q_OBJECT

public:
    explicit Timer( QObject* parent = 0 );

signals:
    void timeout();

private:
    QTimer* m_timer;
    
private slots:
    void onInternalTimeout();
};

#endif // TIMER_H

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#include "timer.h"
 
#include <QDebug>
#include <QTimer>
 
Timer::Timer( QObject* parent )
    : QObject( parent ),
      m_timer( new QTimer( this ) )
{
    m_timer->setInterval( 1000 );
    connect(m_timer, SIGNAL(timeout()), this, SLOT(onInternalTimeout()));
    m_timer->start();
}
 
void Timer::onInternalTimeout()
{
    qDebug() << Q_FUNC_INFO;
    emit timeout();
    qDebug() << "emit timeout() returned";
}

#include "timer.h"

#include <QDebug>
#include <QTimer>

Timer::Timer( QObject* parent )
    : QObject( parent ),
      m_timer( new QTimer( this ) )
{
    m_timer->setInterval( 1000 );
    connect(m_timer, SIGNAL(timeout()), this, SLOT(onInternalTimeout()));
    m_timer->start();
}

void Timer::onInternalTimeout()
{
    qDebug() << Q_FUNC_INFO;
    emit timeout();
    qDebug() << "emit timeout() returned";
}

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import QtQuick 2.0
import CustomComponents 1.0
 
Timer {
    id: timer
    onTimeout: console.log( "onTimeout in QML" )
}

import QtQuick 2.0
import CustomComponents 1.0

Timer {
    id: timer
    onTimeout: console.log( "onTimeout in QML" )
}

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Obviously exporting the Timer class with qmlRegisterType in "CustomComponents" version 1.0

Output is

void Timer::onInternalTimeout() 
onTimeout in QML
emit timeout() returned

void Timer::onInternalTimeout() 
onTimeout in QML
emit timeout() returned

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So emit returns after the "QML slot" has been called. AKA DirectConnection

Cheers,
_

[wysota]

More likely having two properties of type QObject* and two properties of type QString.

Yes, that's what I mean in the last paragraph of my previous post.

Ok, I have to say I don't understand the problem.

I get DirectConnection behavior in a simple test application

I think OP wants a direct connection between objects living in different threads which is a Bad Thing.