comparing destop frameworks, PyQt vs Tkinter, Electron and other Python GUI frameworks

What does PyQt’s signal and slots feature enable?

The signal and slots mechanism in PyQt enables bindings between objects so that changes in state in one object can automatically trigger actions in another object without the two objects knowing anything about each other. This allows for clean separation between UI elements and handling of UI events.

# Signal emitted when button is clicked
self.button.clicked.connect(self.handleButtonClick) 

# Slot that handles button click  
def handleButtonClick(self):
  print("Button clicked!")

What does pyqtSignal() do in PyQt?

pyqtSignal() is used to define custom signals in PyQt classes. This allows creating signals that can carry arbitrary arguments.

class MyClass(QObject):
  signal = pyqtSignal(str, int)

Here a signal called signal is defined that can pass a string and integer.

What are slots in PyQt?

Slots in PyQt are Python methods that can be connected to signals to handle events and trigger responses. They provide an easy way to connect GUI elements like buttons and events like clicks to Python code without complicated callback mechanisms.

# Connect button click to slot
self.button.clicked.connect(self.handleButtonClick)

# Slot method 
def handleButtonClick(self):
  print("Button clicked") 

What are some key differences between PyQt and Tkinter?

• PyQt is more powerful and flexible than Tkinter but has a steeper learning curve.
• PyQt uses Qt’s signal/slot architecture while Tkinter typically uses callback functions.
• PyQt has more extensive widget sets and tools like Qt Designer available.
• PyQt has better performance for complex UIs compared to Tkinter.
• PyQt code is generally more cleanly separated from UI code than Tkinter.

What are some downsides of using Electron compared to Qt?

• Electron apps have much larger download sizes due to being bundled with an entire Chromium instance.
• Electron apps typically use more memory and CPU than native apps built with Qt.
• The performance of Electron apps may not be as good for certain use cases like games or video editing.
• Debugging and optimization of Electron apps is harder because of the additional web layer.
• Advanced native integrations can be harder with Electron.

What does QSettings enable in PyQt?

QSettings allows saving and restoring application settings in a platform-independent way in PyQt. Values can be stored persistently and retrieved later using QSettings.

# Save value
settings = QSettings("MyOrg", "MyApp")
settings.setValue("colour", "red")

# Restore value
settings = QSettings("MyOrg", "MyApp")  
colour = settings.value("colour") # "red"

How can Qt Designer be used with PyQt?

Qt Designer is a visual editor that can be used to build UIs visually by dragging and dropping widgets. The UI files can then be integrated into a PyQt codebase using the uic module to convert the .ui files into Python code.

import uic

form_class = uic.loadUiType("mainwindow.ui")[0] # Load UI

class MainWindow(QMainWindow, form_class): # Create window
  def __init__(self):
    super().__init__()
    self.setupUi(self) # Set up UI

References

https://www.riverbankcomputing.com/static/Docs/PyQt5/signals_slots.html https://www.learnpyqt.com/tutorials/qsettings-ini-style-settings/