Connect all signal from QVector<Element*> to one slot

romain.donze

Hi,

So, I have a QVector<Element*> with Element subclassing QObject and having some signal to emit.

This QVector can change overtime with by append, remove, insert, swap, move etc.

In the parent class, I have one slot that I'd like to connect to all signal in my QVector.

I know I could do that with a for loop

foreach (Element, QVector)
    connect(Element, signal, this, slot)

But as said, this vector will change overtime so I will have to do a connect each time I append or insert an Element.

So my question is simple. Is there an easy way to connect every signal comming from a qvector to one slot?

connect(QVector<Element*>, Element::signal, this, parentClass::slot);

If not would I need to reconnect my signals if I do a swap or insert etc.?

sierdzio

@romain-donze said in Connect all signal from QVector<Element*> to one slot:

If not would I need to reconnect my signals if I do a swap or insert etc.?

Yes you need to do it manually, as far as I know.

romain.donze

And what if I just swap two elements? Will I have to reconnect the signal of those elements? even if I already did it earlier?

QVector<Element*> my_QVector = QVector<Element*>(3)

connect(my_QVector.at(0), &Element::signal, this, &parentClass::slot);
connect(my_QVector.at(1), &Element::signal, this, &parentClass::slot);
connect(my_QVector.at(2), &Element::signal, this, &parentClass::slot);

my_QVector.swap(1,2);

connect(my_QVector.at(1), &Element::signal, this, &parentClass::slot);
connect(my_QVector.at(2), &Element::signal, this, &parentClass::slot);

And what if Elements are pointers?

sierdzio

@romain-donze said in Connect all signal from QVector<Element*> to one slot:

And what if I just swap two elements? Will I have to reconnect the signal of those elements? even if I already did it earlier?
QVector<Element*> my_QVector = QVector<Element*>(3)

connect(my_QVector.at(0), &Element::signal, this, &parentClass::slot);
connect(my_QVector.at(1), &Element::signal, this, &parentClass::slot);
connect(my_QVector.at(2), &Element::signal, this, &parentClass::slot);

my_QVector.swap(1,2);

There is no such method in QVector. I assume you mean swapItemsAt(). No need to reconnect - connection is made between pointers, Qt does not care where you store these pointers and in which order.

connect(my_QVector.at(1), &Element::signal, this, &parentClass::slot);
connect(my_QVector.at(2), &Element::signal, this, &parentClass::slot);
And what if Elements are pointers?

They already are in your example. Storing QObjects on stack is rare, but even in that case - connection is between actual objects, not their index in any vector.

romain.donze

Thank you for your quick reply @sierdzio. so I guess I will have to add a method that connects my signal each time I append or insert an element.

sierdzio

@romain-donze said in Connect all signal from QVector<Element*> to one slot:

Thank you for your quick reply @sierdzio. so I guess I will have to add a method that connects my signal each time I append or insert an element.

And disconnects when it is removed.

gde23

I would consider making your own (subclassed) container for elements.
There you can have methods for appending / removing elements that automatically connect / disconnect the signals when the elements get added / removed.

romain.donze

@gde23 Yes no problem with that. I already have something like this

class vectorOfElement : public QObject
{
    Q_OBJECT
    Q_PROPERTY(QQmlListProperty<Element> Elements READ getElementsQML CONSTANT)
public:
    vectorOfElement(QObject *parent = nullptr);
    ~vectorOfElement();

    void addNewElement(Element*);

    UInt16 getNbElements() const;

    QVector<Element*>* getElements();
    QQmlListProperty<Element> getElementsQML();

signals:
public slots:
private slots:
private:
    static int getNbElements(QQmlListProperty<Element>*);
    static PAViX* getElementFromIndex(QQmlListProperty<Element>*, int);

    QVector<Element*> m_Elements;
};