/*!
* \brief Qt5's signal and slot connection, using pointer to member functions.
*/
void ConnectLambdaTest::testCaseNormalUse() {
// create sender and receiver objects
QScopedPointer<Object> sender ( new Object );
QScopedPointer<Object> receiver ( new Object );
// connect them
connect(sender.data(), &Object::signalTest, receiver.data(), &Object::slotTest);
// emit signal
sender->emitSignal(0x58ef);
// test if slot correclty receive info
QCOMPARE(0x58ef, receiver->checkValue());
}
/*!
* \brief Use lambda with Qt5's new connection syntaxe.
*/
void ConnectLambdaTest::testCaseWithLambda() {
// create sender and receiver objects
// receiver is shared with lambda context
QScopedPointer<Object> sender ( new Object );
QSharedPointer<Object> receiver ( new Object );
// connect them with lambda
connect(sender.data(), &Object::signalTest,
[receiver](int value){ Q_ASSERT(receiver); receiver->setCheckValue(value); });
// emit signal
sender->emitSignal(0xb69d);
// test if slot correclty receive info
QCOMPARE(0xb69d, receiver->checkValue());
}
/*!
* \brief Use QPointer to check pointer in lambda.
* QPointer is Qt's smart pointer, which become nullptr when
* QObject's derived object is deleted. QPointer is copiable,
* then when can copy it directly inside lambda.
*
* In lambda, we can just check pointer with assert, if the receiver
* can have a shorter lifetime than sender, or 'if' statement if
* receiver need to have a longer lifetime than sender.
*/
void ConnectLambdaTest::testCaseLambdaQPointer() {
// create sender and receiver objects
// use QPointer to check pointer before use
QScopedPointer<Object> sender ( new Object );
QPointer<Object> receiver ( new Object );
// connect them with lambda
connect(sender.data(), &Object::signalTest,
[receiver](int value){ Q_ASSERT(receiver); receiver->setCheckValue(value); });
// delete receiver
delete receiver;
// emit signal
sender->emitSignal(0x800a);
// can't test, receiver is nullptr
// QCOMPARE(0x800a, receiver->checkValue());
QFAIL("This test need to fail...");
}
/*!
* \brief Use lambda with Qt5's new connection syntaxe, with invalide pointer.
* The raw pointer become invlide inside the lambda, but the connect is not
* destroy when receiver is deleted. Then, emitting signal call lambda
* with this invalid pointer, and cause a Undefined Behavior (UB).
*
* Note: UB doesn't cause crash every time. When I run this tests (MingW 4.9.2
* and MSVC 2013), the test run like object is valid.
*/
void ConnectLambdaTest::testCaseLambdaAndDeletedObject() {
// create sender and receiver objects
// we want to delete receiver before end of function, the use raw pointer
QScopedPointer<Object> sender ( new Object );
Object* receiver ( new Object );
// connect them with lambda
connect(sender.data(), &Object::signalTest,
[receiver](int value){ Q_ASSERT(receiver); receiver->setCheckValue(value); });
// delete receiver
delete receiver;
receiver = nullptr;
// emit signal
sender->emitSignal(0x2d9b);
// can't test, receiver is nullptr
// QCOMPARE(0x800a, receiver->checkValue());
QFAIL("This test need to fail...");
}