How to handle widget events using PyQt signal and slot mechanism
Signals & Slots Signals and slots are used for communication between objects. The signals and slots mechanism is a central feature of Qt and probably the part that differs most from the features provided by other frameworks.
Signals and slots
You need define signal and slots in your classes. Add to header of your class, for example signals to MainWindow, slots to Computations.
Signals and Slots in Qt5 - woboq.com
Qt5 C++ GUI Programming Cookbook, 2nd Edition is a.