CODEWITHSUNDEEP
qtsignals-slotsqt-signals
Alex Hendren
Alex Hendren

Reputation: 416

Qt Auto Connect New Object's Signal to Existing Slot

I have a simple object library that will be used for storing additional data about variables. As I create each object (to be used as variable), I would like to maintain a QList of these objects. Is there a way to automatically connect all of the newly created object's signals to one slot. The slot belongs to an object within my application.

Object Header ezbool.h

class EZBool : public QObject
{
    Q_OBJECT
public:
    explicit EZBool(QObject *parent = 0);
    EZBool(QString boolName, bool initialValue, IOTYPE type);   
    //Removed Member Functions      
signals:
    void localEZBool_Created(EZBool *me);
private:
    QString name;
    bool value;
    IOTYPE ioType;
};

Object Constructor ezbool.cpp

EZBool::EZBool(QString boolName, bool initialValue, IOTYPE type)
{
    name = boolName;
    value = initialValue;
    ioType = type;
    emit localEZBool_Created(this);
}

Slot Implementation fbtest.cpp

void TestFB::on_localEZBool_Created(EZBool *newVar)
{
    qDebug() << "Auto Connect worked??";
    //Handle new variable by adding to QList
}

Objects are created in the following manner within fbtest.cpp:

void TestFB::initialize()
{
    mpOnCmd     = new EZBool("MpOnCmd", false, IO_INPUT);
    zeroSpeed   = new EZBool("ZeroSpeed", false, IO_INPUT);

}

I have tried matching Qt's auto connect feature, but no luck. The auto connect ability was referenced from the following:

Automatic Connections

Qt Project Forums

I do not want to manually connect every signal after instantiating each new object. In the following manner:

connect(ezBool, SIGNAL(localEZBool_Created(EZBool*)),
        this, SLOT(on_localEZBool_Created(EZBool*)));

Does anyone have any recommendations or suggestions? Thank you!

Upvotes: 2

Views: 2373

Answers (2)

vahancho
vahancho

Reputation: 21220

To solve objects list auto-population I wouldn't use signal/slot mechanism at all. It actually seems to be an overkill and unnecessary dependency from QObject. Instead, I would propose the following solution that, IMO, much simpler.

Define the list that will store newly created objects. You can read it whenever you want:

static QList<EZBool *> Objects;

Class EZBool will automatically populate the list with newly created objects:

class EZBool
{
public:    
    EZBool(QString boolName, bool initialValue, IOTYPE type)
        :
            name(boolName),
            value(initialValue),
            ioType(type)
    {
        Objects.push_back(this);
    }
private:
    QString name;
    bool value;
    IOTYPE ioType;
};

This class is responsible for new EZBool objects creation.

class TestFB
{
public:
    void initialize()
    {
        new EZBool("MpOnCmd", false, IO_INPUT);
        new EZBool("ZeroSpeed", false, IO_INPUT);
    } 
};

Upvotes: 0

ratchet freak
ratchet freak

Reputation: 48196

you can override childEvent in TestFB and then react to it for the ChildAdded

void TestFB::childEvent(QChildEvent * event)
{
    if(event.added())
    {
        EZBool child = qobject_cast<EZBool*>(event.child());
        if(child)
        {
            qDebug() << "Auto Connect worked??";
            //Handle new variable by adding to QList
        }
    }
}

this needs the parent of EZBool to be set to the TestFB (preferably in the constructor)

mpOnCmd     = new EZBool("MpOnCmd", false, IO_INPUT, this);
zeroSpeed   = new EZBool("ZeroSpeed", false, IO_INPUT, this);

and add a QObject *parent=0 parameter to the custom constructor and pass it to the super class

EZBool::EZBool(QString boolName, bool initialValue, IOTYPE type, QObject p)
: QObject(p)
{
    name = boolName;
    value = initialValue;
    ioType = type;
}

Upvotes: 1

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