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Python GUI Development with Qt - QtDesigner's Signal-Slot Editor, Tab Order Management - Video 12 - Duration. QT connect signal to slot - Duration: 7:26. Dave Burchill 6,389 views. Qt documentation: Connecting overloaded signals/slots. While being better in many regards, the new connection syntax in Qt5 has one big weakness: Connecting overloaded signals and slots. Detailed Description. QObject is the heart of the Qt Object Model.The central feature in this model is a very powerful mechanism for seamless object communication called signals and slots.You can connect a signal to a slot with connect and destroy the connection with disconnect. To avoid never ending notification loops you can temporarily block signals with blockSignals.
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Unlike a console mode application, which is executed in a sequential manner, a GUI based application is event driven. Functions or methods are executed in response to user’s actions like clicking on a button, selecting an item from a collection or a mouse click etc., called events.
Widgets used to build the GUI interface act as the source of such events. Each PyQt widget, which is derived from QObject class, is designed to emit ‘signal’ in response to one or more events. The signal on its own does not perform any action. Instead, it is ‘connected’ to a ‘slot’. The slot can be any callable Python function.
In PyQt, connection between a signal and a slot can be achieved in different ways. Following are most commonly used techniques −
A more convenient way to call a slot_function, when a signal is emitted by a widget is as follows −
Suppose if a function is to be called when a button is clicked. Here, the clicked signal is to be connected to a callable function. It can be achieved in any of the following two techniques −
or
Example
In the following example, two QPushButton objects (b1 and b2) are added in QDialog window. We want to call functions b1_clicked() and b2_clicked() on clicking b1 and b2 respectively.
When b1 is clicked, the clicked() signal is connected to b1_clicked() function
Qt Connect Two Signal
When b2 is clicked, the clicked() signal is connected to b2_clicked() function
Example
Qt Connect Signal To Signal
The above code produces the following output −