Dev Blog

Summary ​

Conclusions ​

A GUI application reacts to events. Layouts make a form adaptive, signals connect components, and slots perform short actions. Computations should be kept separate from widgets. Validation must be understandable to the user and keep the program in a correct state.

Self-check questions ​

  1. Why do you need a single QApplication and a call to exec()?
  2. Why does show() not replace the event loop?
  3. How does the widget tree differ from the layout tree?
  4. When can a local widget without a parent disappear?
  5. Which tasks are the four main layouts intended for?
  6. Why is QSpinBox.value() better than reading its text?
  7. What do the textChanged and textEdited signals mean?
  8. Why are parentheses not added after the function name in connect?
  9. Where do you declare a custom Signal, and how do you emit a value?
  10. How do you avoid a loop in two-way recalculation?
  11. Why does a validator allow intermediate states?
  12. How does a single action appear in both a menu and a toolbar?
  13. Why can a timeout not be considered an exact time measurement?
  14. How do pyside6-uic and QUiLoader differ?
  15. Which checks cannot be replaced by offscreen tests?