Why i am getting error when use new signal slot method ?

[Qt embedded developer]

I am using below code in constructor. BlinkLabel is public slot.

when i use below line in my constructor error not come.
QObject::connect(qTScanning, SIGNAL(timeout()), this, SLOT(BlinkLabel()));

but when i use new signal slot method i am getting error:

• error: no matching function for call to &G3_Scan::BlinkLabel

• error: invalid use of incomplete type 'struct QtPrivate::QEnableIf<false, QMetaObject::Connection>'

• /usr/include/x86_64-linux-gnu/qt5/QtCore/qobject.h:293: error: invalid use of incomplete type 'struct QtPrivate::QEnableIf<false, QMetaObject::Connection>'

INIT_OBJ(qTScanning);
    qTScanning  = new QTimer(this);
    //        time1->setSingleShot(true);
    QObject::connect(&qTScanning, &QTimer::timeout, this, &G3_Scan::BlinkLabel);
    qTScanning->start(500);

How to resolve this error? what mistake i have done ?

[KroMignon]

@Qt-embedded-developer said in Why i am getting error when use new signal slot method ?:

QObject::connect(&qTScanning, &QTimer::timeout, this, &G3_Scan::BlinkLabel);

As far as I can see, qTScanning is a pointer
==> QObject::connect(qTScanning, &QTimer::timeout, this, &G3_Scan::BlinkLabel); is more correct!

[raven-worx]

@Qt-embedded-developer
are there multiple BlinkLabel methods available (with different signatures)?
if so, see qOverload

[KroMignon]

@Qt-embedded-developer said in Why i am getting error when use new signal slot method ?:

QObject::connect(&qTScanning, &QTimer::timeout, this, &G3_Scan::BlinkLabel);

As far as I can see, qTScanning is a pointer
==> QObject::connect(qTScanning, &QTimer::timeout, this, &G3_Scan::BlinkLabel); is more correct!

[Qt embedded developer]

@raven-worx no there is only one public slot named BlinkLabel()

[raven-worx]

@Qt-embedded-developer
the this pointer is an instance of the class G3_Scan?

btw: using the old connect syntax might silently fail, but it doesnt mean that the old syntax is working. You would need to check the return value if the connection was successfully established.

[Qt embedded developer]

@raven-worx i made the mistake due to use of &qTScanning. now my code is working . but i am not getting why i can not use &qTScanning?

[CP71]

@Qt-embedded-developer
Hi
because qTScanning is already a pointer

[Qt embedded developer]

@raven-worx How to check return value of successful connection ?

[raven-worx]

@Qt-embedded-developer
return true -> success, false -> failed

but simply dont use the old connect syntax anymore

[Qt embedded developer]

@raven-worx sorry but can you give sample example ?

[raven-worx]

@Qt-embedded-developer

if( QObject::connect(qTScanning, SIGNAL(timeout()), this, SLOT(BlinkLabel())) )
    qDebug() << "GOOD";
else
    qDebug() << "BAD";

[Qt embedded developer]

@raven-worx Thank you

[Qt embedded developer]

This post is deleted!

[CP71]

@Qt-embedded-developer
try delete the build folder from file explorer and rebuild all