CODEWITHSUNDEEP
c++qtqt5
user9910916
user9910916

Reputation:

Qt: How to connect static signal from different class to slot?

So let's suppose I've got a regular Qt class MyQtClass and a class MyClass with ONLY static members. If I want to access the ui of MyQtClass I have to use Signals and Slots. So I create a static Signal (static so I can just invoke it like MyClass::mySignal();) and a slot in the Qt class. How can I connect the static signal from MyClass with the slot from the Qt class, without having an object of MyClass, since it has only got static members? I know that classes with only static members isn't considered as a good design in c++ but I'm too far into the project by now and I want to know if there's a way to do it with only static members. Thanks in Advance! Code: MyQtClass.h:

#include "ui_MyQtClass.h"

class MyQtClass : public QMainWindow
{
    Q_OBJECT

public:
    MyQtClass(QWidget *parent = Q_NULLPTR);

    Q_SLOT void mySlot();

private:
    Ui::MyQtClassClass ui;
};

MyClass.h:

#pragma once
#include <QtWidgets/QMainWindow>

class MyClass : public QObject
{
public:
    static void myFunction1();
    static void myFunction2();
    /*--- More Stuff ---*/


    Q_SIGNAL static void mySignal();
};

Upvotes: 2

Views: 2328

Answers (1)

eyllanesc
eyllanesc

Reputation: 243993

As indicated in this thread it is not possible to emit static signals since it is always associated with a QObject, as an alternative they create a singleton that would be equivalent to what you want.

#include <QtCore>
class Receiver: public QObject
{
    Q_OBJECT
public:
    using QObject::QObject;
    Q_SLOT void mySlot(){
        qDebug()<< __PRETTY_FUNCTION__;
        QCoreApplication::quit();
    }
};
class Sender: public QObject
{
    Q_OBJECT
    using QObject::QObject;
public:
    static Sender& instance(){
        static Sender m_instance;
        return m_instance;
    }
    static void myFunction1(){
        emit instance().mySignal();
    }
    Q_SIGNAL void mySignal();
};
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    Receiver r;
    QObject::connect(&Sender::instance(), &Sender::mySignal, &r, &Receiver::mySlot);
    QTimer::singleShot(1000, &Sender::myFunction1);
    return a.exec();
}
#include "main.moc"

Upvotes: 2

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