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.
c++ - Qt events and signal/slots - Stack Overflow
Signals and slot introduction Consider this example ...
Qt Tutorial 16: Signals and Slots nâng cao - DevNT.org
In this video, you will learn about communicating between two threads using Qt signals and slots and what is really happening under the hood when you do that...
Delete signal/slot connection from Qt Designer
To establish a signal and slot connection between two widgets in a dialog, you first need to switch to Qt Designer's Edit Signals/Slots mode.