Graphical applications (GUI) are event-driven, unlike console or terminal applications. A users action like clicks a button or selecting an item in a list is called an event.

1. Connecting in Qt 5. There are several ways to connect a signal in Qt 5. Qt 5 continues to support the old string-based syntax for connecting signals and slots defined in a QObject or any class that inherits from QObject (including QWidget).
2. The keywords such as public, private are ignored for Qt slots. All slots are actually public and can be connected. Share follow answered Feb 5 '12 at 7:29.
3. Signals and slots are loosely coupled: A class which emits a signal neither knows nor cares which slots receive the signal. Qt's signals and slots mechanism ensures that if you connect a signal to a slot, the slot will be called with the signal's parameters at the right time. Signals and slots can take any number of arguments of any type.
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If an event takes place, each PyQt5 widget can emit a signal. A signal does not execute any action, that is done by a slot.

Likewise, there is a QD macro for use inside method implementations so you can use d as a pointer to the private class. The QPRIVATESLOT macro takes a pointer to your private class, and we will take advantage of the dfunc method to get it. Next is the signature of the private class' method to call.

Related course:
Create GUI Apps with PyQt5

Signals and slot introduction
Consider this example:

The button click (signal) is connected to the action (slot). In this example, the method slot_method will be called if the signal emits.

This principle of connecting slots methods or function to a widget, applies to all widgets,

or we can explicitly define the signal:

PyQt supports many type of signals, not just clicks.

Example
We can create a method (slot) that is connected to a widget. A slot is any callable function or method.

Private Slots Qt 500

On running the application, we can click the button to execute the action (slot).

Private Slots Qt 5 0

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