QSignalSpy Class
The QSignalSpy class enables introspection of signal emission. More...
Public Functions
QSignalSpy(const QObject *object, PointerToMemberFunction signal) | |
QSignalSpy(const QObject *object, const char *signal) | |
bool | isValid() const |
QByteArray | signal() const |
bool | wait(int timeout = 5000) |
Related Non-Members
typedef | QObjectList |
QList<T> | qFindChildren(const QObject *obj, const QRegExp ®Exp) |
uint | qHash(const QMimeType &key, uint seed) |
uint | qHash(const QUuid &uuid, uint seed) |
uint | qHash(const QUrlQuery &key, uint seed) |
uint | qHash(const QRegularExpression &key, uint seed) |
uint | qHash(const QLocale &key, uint seed) |
uint | qHash(const QPersistentModelIndex &index, uint seed) |
uint | qHash(const QRegExp &key, uint seed) |
uint | qHash(const QList<T> &key, uint seed) |
uint | qHash(const QSet<T> &key, uint seed) |
uint | qHash(const QMultiHash<Key, T> &key, uint seed) |
uint | qHash(const QHash<Key, T> &key, uint seed) |
uint | qHash(const QDateTime &key, uint seed) |
uint | qHash(const QDate &key, uint seed) |
uint | qHash(const QTime &key, uint seed) |
uint | qHash(const QVersionNumber &key, uint seed) |
T | qobject_cast(QObject *object) |
T | qobject_cast(const QObject *object) |
bool | operator<(const QVersionNumber &lhs, const QVersionNumber &rhs) |
bool | operator<(QDeadlineTimer d1, QDeadlineTimer d2) |
bool | operator<(const QElapsedTimer &v1, const QElapsedTimer &v2) |
bool | operator<(const QCollatorSortKey &lhs, const QCollatorSortKey &rhs) |
bool | operator<(const QVarLengthArray<T, Prealloc1> &lhs, const QVarLengthArray<T, Prealloc2> &rhs) |
bool | operator<(const QList<T> &lhs, const QList<T> &rhs) |
bool | operator<=(const QVersionNumber &lhs, const QVersionNumber &rhs) |
bool | operator<=(QDeadlineTimer d1, QDeadlineTimer d2) |
bool | operator<=(const QUuid &lhs, const QUuid &rhs) |
bool | operator<=(const QVarLengthArray<T, Prealloc1> &lhs, const QVarLengthArray<T, Prealloc2> &rhs) |
bool | operator<=(const QList<T> &lhs, const QList<T> &rhs) |
bool | operator>(const QVersionNumber &lhs, const QVersionNumber &rhs) |
bool | operator>(QDeadlineTimer d1, QDeadlineTimer d2) |
bool | operator>(const QVarLengthArray<T, Prealloc1> &lhs, const QVarLengthArray<T, Prealloc2> &rhs) |
bool | operator>(const QList<T> &lhs, const QList<T> &rhs) |
bool | operator>=(const QVersionNumber &lhs, const QVersionNumber &rhs) |
bool | operator>=(QDeadlineTimer d1, QDeadlineTimer d2) |
bool | operator>=(const QUuid &lhs, const QUuid &rhs) |
bool | operator>=(const QVarLengthArray<T, Prealloc1> &lhs, const QVarLengthArray<T, Prealloc2> &rhs) |
bool | operator>=(const QList<T> &lhs, const QList<T> &rhs) |
QDataStream & | operator>>(QDataStream &stream, QRectF &rectangle) |
QDataStream & | operator>>(QDataStream &stream, QRect &rectangle) |
QDataStream & | operator>>(QDataStream &stream, QSizeF &size) |
QDataStream & | operator>>(QDataStream &stream, QSize &size) |
QDataStream & | operator>>(QDataStream &stream, QMarginsF &m) |
QDataStream & | operator>>(QDataStream &stream, QMargins &m) |
QDataStream & | operator>>(QDataStream &s, QUuid &id) |
QDataStream & | operator>>(QDataStream &in, QUrl &url) |
QDataStream & | operator>>(QDataStream &in, QDateTime &dateTime) |
QDataStream & | operator>>(QDataStream &in, QTime &time) |
QDataStream & | operator>>(QDataStream &in, QDate &date) |
QDataStream & | operator>>(QDataStream &in, QBitArray &ba) |
QDataStream & | operator>>(QDataStream &in, QList<T> &list) |
QDataStream & | operator>>(QDataStream &in, QLinkedList<T> &list) |
QDataStream & | operator>>(QDataStream &in, QRegularExpression &re) |
QDataStream & | operator>>(QDataStream &in, QRegExp ®Exp) |
QDataStream & | operator>>(QDataStream &in, QVector<T> &vector) |
QDataStream & | operator>>(QDataStream &in, QHash<Key, T> &hash) |
QDataStream & | operator>>(QDataStream &stream, QPointF &point) |
QDataStream & | operator>>(QDataStream &stream, QEasingCurve &easing) |
QDataStream & | operator>>(QDataStream &in, QVersionNumber &version) |
QDataStream & | operator>>(QDataStream &stream, QLine &line) |
QDataStream & | operator>>(QDataStream &stream, QLineF &line) |
Macros
QT_NO_NARROWING_CONVERSIONS_IN_CONNECT | |
Q_CLASSINFO(Name, Value) | |
Q_DISABLE_COPY(Class) | |
Q_DISABLE_COPY_MOVE(Class) | |
Q_DISABLE_MOVE(Class) | |
Q_EMIT | |
Q_ENUM(...) | |
Q_ENUM_NS(...) | |
Q_FLAG(...) | |
Q_FLAG_NS(...) | |
Q_GADGET | |
Q_INTERFACES(...) | |
Q_INVOKABLE | |
Q_NAMESPACE | |
Q_OBJECT | |
Q_PROPERTY(...) | |
Q_REVISION | |
Q_SET_OBJECT_NAME(Object) | |
Q_SIGNAL | |
Q_SIGNALS | |
Q_SLOT | |
Q_SLOTS |
Additional Inherited Members
- 1 property inherited from QObject
- 1 public slot inherited from QObject
- 2 signals inherited from QObject
- 9 static public members inherited from QObject
- 3 static public members inherited from QList
- 9 protected functions inherited from QObject
Detailed Description
QSignalSpy can connect to any signal of any object and records its emission. QSignalSpy itself is a list of QVariant lists. Each emission of the signal will append one item to the list, containing the arguments of the signal.
The following example records all signal emissions for the clicked()
signal of a QCheckBox:
QCheckBox *box = ...; QSignalSpy spy(box, SIGNAL(clicked(bool))); // do something that triggers the signal box->animateClick(); QCOMPARE(spy.count(), 1); // make sure the signal was emitted exactly one time QList<QVariant> arguments = spy.takeFirst(); // take the first signal QVERIFY(arguments.at(0).toBool() == true); // verify the first argument
spy.takeFirst()
returns the arguments for the first emitted signal, as a list of QVariant objects. The clicked()
signal has a single bool argument, which is stored as the first entry in the list of arguments.
The example below catches a signal from a custom object:
QSignalSpy spy(myCustomObject, SIGNAL(mySignal(int,QString,double))); myCustomObject->doSomething(); // trigger emission of the signal QList<QVariant> arguments = spy.takeFirst(); QVERIFY(arguments.at(0).type() == QVariant::Int); QVERIFY(arguments.at(1).type() == QVariant::String); QVERIFY(arguments.at(2).type() == QVariant::double);
Note: Non-standard data types need to be registered, using the qRegisterMetaType() function, before you can create a QSignalSpy. For example:
qRegisterMetaType<SomeStruct>(); QSignalSpy spy(&model, SIGNAL(whatever(SomeStruct)));
To retrieve the instance, you can use qvariant_cast:
// get the first argument from the first received signal: SomeStruct result = qvariant_cast<SomeStruct>(spy.at(0).at(0));
Member Function Documentation
QSignalSpy::QSignalSpy(const QObject *object, PointerToMemberFunction signal)
Constructs a new QSignalSpy that listens for emissions of the signal from the QObject object. If QSignalSpy is not able to listen for a valid signal (for example, because object is nullptr
or signal does not denote a valid signal of object), an explanatory warning message will be output using qWarning() and subsequent calls to isValid()
will return false.
Example:
QSignalSpy spy(myPushButton, &QPushButton::clicked);
This function was introduced in Qt 5.4.
QSignalSpy::QSignalSpy(const QObject *object, const char *signal)
Constructs a new QSignalSpy that listens for emissions of the signal from the QObject object. If QSignalSpy is not able to listen for a valid signal (for example, because object is nullptr
or signal does not denote a valid signal of object), an explanatory warning message will be output using qWarning() and subsequent calls to isValid()
will return false.
Example:
QSignalSpy spy(myPushButton, SIGNAL(clicked(bool)));
bool QSignalSpy::isValid() const
Returns true
if the signal spy listens to a valid signal, otherwise false.
QByteArray QSignalSpy::signal() const
Returns the normalized signal the spy is currently listening to.
bool QSignalSpy::wait(int timeout = 5000)
Starts an event loop that runs until the given signal is received. Optionally the event loop can return earlier on a timeout (in milliseconds).
Returns true
if the signal was emitted at least once in timeout milliseconds, otherwise returns false
.
Example:
QVERIFY(spy.wait(1000));
This function was introduced in Qt 5.0.