Qt signal for a specific object slot

Question

I would like to know which of the following is the correct way to do things with a signal / slot in Qt.

I need a way to have multiple instances of the dialog, i.e. Aand B. And I need to say Ato print “A” and Bto print “B” from another thread. Therefore, I believe that I need something like:

OPTION 1) A->print("A") andB->print("B")

or better to do:

OPTION 2) emit print("A") and emit print("B")and use a method that I do not know, so only Acatch "A" and only Bcatch "B" ,.

I have option 1 that works as follows:

class myClass : public QMainWindow
{
    Q_OBJECT

public:
    myClass (QWidget *parent = 0, Qt::WFlags flags = 0);
    ~myClass ();
    void doPrint(char* text)
    {
         emit mySignal(text);
    }
private:
    Ui::myClass ui;

public slots:
    void newLog(char* msg);

signals:
     void mySignal(char* msg);
};

myClass::myClass(QWidget *parent, Qt::WFlags flags) : QMainWindow(parent, flags)
{
    ui.setupUi(this);
    connect(this, SIGNAL(mySignal(char*)), this, SLOT(newLog(char*)));
}

void myClass::newLog(char* msg)
{
    ui.textEdit->append(msg);
}

and then all I need to do is:

myClass* instanceA = new myClass();
myClass* instanceB = new myClass();
instanceA->doPrint("A");
instanceB->doPrint("B");

is that right?

Thanks!

Answer 1

, Meta-Object System . - QMetaObject::invokeMethod

QThread . .: http://blog.qt.digia.com/blog/2010/06/17/youre-doing-it-wrong/

void otherClass::printTo(myClass* instance, char* text)
{
    QMetaObject::invokeMethod(instance,        // pointer to a QObject
                              "doPrint",       // member name (no parameters here)
                              Qt::QueuedConnection,     // connection type
                              Q_ARG(char*, text));     // parameters
}

void myClass::doPrint(char* text)
{
    ui.textEdit->append(text);
}

myClass* instanceA = new myClass();
myClass* instanceB = new myClass();
printTo(instanceA, "A");
printTo(instanceB, "B");

char * , Q_DECLARE_METATYPE(char*);

qRegisterMetaType<char*>("charPtr");

Answer 2

, 1. , doPrint(), mySignal ( , myClass). QThread, , - :

class myThread : public QThread
{
    Q_OBJECT

public:
    myThread (QWidget *parent = 0 ) : QThread(parent) {}
    ~myThread () {}
    void run(char* text)
    {
         emit mySignal(text);
    }

signals:
     void mySignal(char* msg);
};

- :

myClass* instanceA = new myClass();
myThread* threadA = new myThread();
connect(threadA, SIGNAL(mySignal(char*)), instanceA, SLOT(newLog(char*)), Qt::QueuedConnection);
threadA->run( "A" );

, - run, , threadA. , myClass, , . , , myClass, .