Question

I tried declaring a signal in a prototype and then connecting it is script funcition for some reason it does not work as I hoped. My code is as follows. Could some one help me in this.

What I expected was, once I called p.setText('New String') in the script code, since setText emits the textChanged signal it should invoke the slot which is catchSignal(text) already connected in the script code.

Prototype header

#ifndef SCRIPTACTION_H
#define SCRIPTACTION_H

#include <QObject>
#include <QtScript>

class ScriptAction : public QObject , public QScriptable
{
    Q_OBJECT

 public:
    ScriptAction(QObject *parent = 0);

 signals:
    void textChanged(const QString changedString);

};

#endif // SCRIPTACTION_H

Class

#include "scriptaction.h"
#include <QAction>

Q_DECLARE_METATYPE(QAction*)


ScriptAction::ScriptAction(QObject *parent) : QObject(parent)
{
}

Main Class

#include <QApplication>
#include <QDebug>
#include <QAction>
#include "scriptaction.h"
#include <QPushButton>

Q_DECLARE_METATYPE(QAction*)

QScriptValue qAction_Constructor(QScriptContext *ctx, QScriptEngine *eng)
{
    qDebug() << "QAction is called";
    if(ctx->isCalledAsConstructor())
    {
        QObject *parent = ctx->argument(0).toQObject();
        QAction *action = new QAction("Test",parent);
        return eng->newQObject(action, QScriptEngine::ScriptOwnership);
    } else {
        return QString("invalid call. Use new Constructor");
    }
}

int main(int argc, char *argv[])
{
    QApplication app(argc,argv);
    QScriptEngine engine;
    //Evaluating a simaple expresssion
    qDebug() << engine.evaluate("1+2").toNumber();
    QPushButton button;
    QScriptValue buttonScript= engine.newQObject(&button);
    engine.globalObject().setProperty("button", buttonScript);
    engine.evaluate("button.text ='Hello Text'; button.show()");

    //QAction Prototype
    ScriptAction qsAction ;
    QScriptValue script_proto = engine.newQObject(&qsAction);
    engine.setDefaultPrototype(qMetaTypeId<QAction*>(), script_proto);
    QScriptValue ctor = engine.newFunction(qAction_Constructor , script_proto);
    QScriptValue metaObject = engine.newQMetaObject(&QObject::staticMetaObject, ctor);
    engine.globalObject().setProperty("QSAction" , metaObject);
    engine.evaluate("var p = new QSAction(button);p.textChanged.connect(catchSignal);");
    engine.evaluate("function catchSignal(text) { print ('PROTOTYPE SIGNAL IS CALLED ',text); } p.setText('New String'); " );
    return app.exec();
}

Answer 1

I got rid of the issue, and now I see the signal is being triggered and slot is called properly.

All I did was moving the code to a separate script file and start using the QScriptDebugger to see its output. Then I figured there was an error and the code is edited to work.

Anyone who wants an example prototype class, this will hopefully be a good guideline.