Due to the tight integration of the QML engine with the Qt meta-object systemany functionality that is appropriately exposed by a QObject -derived class is accessible from QML code.
Deleting a QObject while pending events are waiting to be delivered can cause a crash. For example, below is a Message class with an author property. This is because, in the ChildAdded case, the child is not yet fully constructed, and in the ChildRemoved case it might have been destructed already.
If you want to compare signal with a specific signal, you can use QMetaMethod:: This function can be invoked via the meta-object system and from QML. See also findChildfindChildrenparentand setParent.
A slot can be connected to a given signal if the signal has at least as many arguments as the slot, and there is an implicit conversion between the types of the corresponding arguments in the signal and the slot. In particular, it determines whether a particular q_invokable slots is delivered to a slot immediately or queued for delivery at a later time.
By default, a signal is emitted for every connection you make; two signals are emitted for duplicate connections.
In addition, any attempts to bind to the property from QML will produce a runtime warning from the engine. All child objects are deleted. Connection that represents a handle to a connection if it successfully connects the signal to the slot. The return value is the previous value of signalsBlocked.
If a signal is connected to several slots, the slots are activated in the same order as the order the connection was made, when the signal is emitted The function returns an handle to a connection if it successfully connects the signal to the slot.
If you pass the Qt:: ConnectionType type but it uses QMetaMethod to specify signal and method. However, you should take care that any objects used within the functor are still alive when the signal is emitted.
Note that the list order changes when QWidget children are raised or lowered. We do not recommend holding pointers to child objects from outside the parent.
The destructor of a parent object destroys all child objects. A signal can be connected to many slots and signals. This function was introduced in Qt 5. See also deleteLater and QPointer. Returns a handle to the connection that can be used to disconnect it later. You must not delete the QObject directly if it exists in a different thread than the one currently executing.
This means that whenever the signal is emitted — as it is when the author changes in Message:: All signals to and from the object are automatically disconnected, and any pending posted events for the object are removed from the event queue.
AutoConnection Creates a connection of the given type from the signal in the sender object to the method in the receiver object.
UniqueConnections do not work for lambdas, non-member functions and functors; they only apply to connecting to member functions. This function violates the object-oriented principle of modularity. Note that entering and leaving a new event loop e. This can be used to expose a group of related properties that describe a set of attributes for a type.
ChildRemoved events are sent to objects when children are added or removed. There are cases where a property's value is set at object construction time, and does not subsequently change.
Member Function Documentation
AutoConnection ; The connection will automatically disconnect if the sender or the context is destroyed. See also connect and disconnectNotify.
The grouped property's sub-properties may be modified from QML but the magic city casino miami address property object itself will never change, whereas an object-type property may be assigned a new object value from QML at any time. Creates a connection from signal in sender object to functor, and returns a handle to the connection The signal must be a function declared as a signal in the header.
Returns true if the connection is successfully broken; otherwise returns false.