What argument types for Signal/Slot?

[DPinLV]

Hello,

I've been reading a few posts and think I am suffering from too much information. I'm trying to find out why my QObject::connect call returns false when I use signal/slot methods with signatures that contain my own type (class DataTabParser):

struct parsedDataTag
{
	char* data_value;
	unsigned int data_length;
};
class DataTabParser
{
	public:
		DataTabParser ();
		~DataTabParser ();
 
		bool parseTabData (const char* parse_string, unsigned int total_length);
		const char* getDataValue (GameUpdateIndices index);
 
	private:
		QString m_original_data;
		vector<struct parsedDataTag*>	m_queue_data;
		unsigned int m_values_count;
};

struct parsedDataTag
{
	char* data_value;
	unsigned int data_length;
};
class DataTabParser
{
	public:
		DataTabParser ();
		~DataTabParser ();

		bool parseTabData (const char* parse_string, unsigned int total_length);
		const char* getDataValue (GameUpdateIndices index);

	private:
		QString m_original_data;
		vector<struct parsedDataTag*>	m_queue_data;
		unsigned int m_values_count;
};

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But, if I use a signal/slot methods with a QString or a char*or an int, etc. as arguments the connect returns true.

I see this error on the following connect call:

QObject::connect(m_emitter_class, 
                     SIGNAL(addParsedDataSignal (DataTabParser *&)),
                     m_pkr_receiver_class,
                     SLOT(addToTable(class DataTabParser *&)),
                     Qt::QueuedConnection);

QObject::connect(m_emitter_class, 
                     SIGNAL(addParsedDataSignal (DataTabParser *&)),
                     m_pkr_receiver_class,
                     SLOT(addToTable(class DataTabParser *&)),
                     Qt::QueuedConnection);

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From Output Window:

Object::connect: No such slot QTPokerClient::addToTable(class DataTabParser*&)
Object::connect: (receiver name: 'QTPokerClientClass')

Then, after reading the following post I'm confused if I decide to use a QString, do I use a reference, do I use a const, what?

http://www.qtcentre.org/forum/f-qt-p...-qt4-3173.html

Here is my problem... I receive data on a socket, and I need to somehow get that data parsed and then inserted into a QTableWidget, and calling the Table draw code from the thread that receives the socket communication does not display properly (nothing displays).

Thanks for any help you all can provide,
Derrick

[sumsin]

SLOT(addToTable(class DataTabParser *&)),

SLOT(addToTable(class DataTabParser *&)),

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don't put class in class DataTabParser *&

in your connect statement

QObject::connect(m_emitter_class,
SIGNAL(addParsedDataSignal (DataTabParser *&)),
m_pkr_receiver_class, SLOT(addToTable(class DataTabParser *&)),
Qt::QueuedConnection);

QObject::connect(m_emitter_class,
SIGNAL(addParsedDataSignal (DataTabParser *&)),
m_pkr_receiver_class, SLOT(addToTable(class DataTabParser *&)),
Qt::QueuedConnection);

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[jacek]

SIGNAL(addParsedDataSignal (DataTabParser *&))

You can't pass references through a signal/slot connection. Either use SIGNAL(addParsedDataSignal( DataTabParser * )) or SIGNAL(addParsedDataSignal( const DataTabParser& )).

If you use the latter, make sure you have a copy constructor and operator= implemented. You will also need this:

qRegisterMetaType< DataTabParser >( "DataTabParser" );

qRegisterMetaType< DataTabParser >( "DataTabParser" );

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[DPinLV]

Jacek I'm confused when you say I can't pass references through Signal/Slots because this connect statement works and I am able to send data.

QObject::connect(m_emitter_class, 
                     SIGNAL(addParsedDataSignalQString (QString const& )),
                     m_pkr_receiver_class,
                     SLOT(addToTable___(QString const&)),
                     Qt::QueuedConnection);

QObject::connect(m_emitter_class, 
                     SIGNAL(addParsedDataSignalQString (QString const& )),
                     m_pkr_receiver_class,
                     SLOT(addToTable___(QString const&)),
                     Qt::QueuedConnection);

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Is this because I am using a QT type, QString?

Thank you.

[jacek]

Is this because I am using a QT type, QString?

No, it works, because you use a const reference. In case of queued connections, it works the same way as:

QObject::connect(m_emitter_class, 
                     SIGNAL(addParsedDataSignalQString(QString)),
                     m_pkr_receiver_class,
                     SLOT(addToTable___(QString)),
                     Qt::QueuedConnection);

QObject::connect(m_emitter_class, 
                     SIGNAL(addParsedDataSignalQString(QString)),
                     m_pkr_receiver_class,
                     SLOT(addToTable___(QString)),
                     Qt::QueuedConnection);

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[DPinLV]

Thanks again jacek!

I see from the documentation why that works with queue Connections:

enum Qt::ConnectionType
With queued connections, the parameters must be of types that are known to Qt's meta-object system, because Qt needs to copy the arguments to store them in an event behind the scenes

Thanks.