Working with Signals and Slots in PyQt5

In this PyQt5 tutorial we want to learn about Working with Signals and Slots in PyQt5, so PyQt5 is one of the best libraries for building GUI applications in Python, and signals and slots in PyQt5 are one of the key features which allows you to communicate between different components of an application.



What is PyQt5 Signals and Slots ?

In PyQt5, signals and slots are mechanisms that is used for communication between different parts of a program. Signals allows objects to notify other objects when certain events occur. They are defined as methods in a class, and when triggered, they emit a signal. For example, a button click or a value change in a widget can be considered as a signal. on the other hand Slots are methods that can be connected to signals. When a signal is emitted, any connected slots are executed. Slots can perform some specific actions or handle the signal in a desired way.



Let’s talk about a simple example where we have a GUI application with a button and a label. we want that when a user clicks on the button, we want to change the text of the label, now clicking the button should trigger a signal, and a connected slot will update the label with a specific text.



This is the complete code for this article 



So now let’s describe our code, in the MyApplication class, we have initialized main window with a title. after that we creates a button and a label as member variables. then we connect the clicked signal of the button to the update_label slot. and lastly we define the update_label method, which sets the text of the label.




In here we have created an instance of QApplication and run the event loop to launch the GUI:




Run the complete code and this will be the result, when you click on the button the label text will be changed.

Working with Signals and Slots in PyQt5
Working with Signals and Slots in PyQt5



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