Lesson Notes 1: Introduction to Event-Driven Programming (EDP)

The main principle of event-driven programming is:

• Sequential execution of code

• Execution of code in response to events

• Execution of code in parallel

• Execution of code without any events

Answer explanation

Event-driven programming focuses on executing code in response to specific events, such as user actions or messages, rather than following a strict sequence. This makes 'Execution of code in response to events' the correct choice.

Identify the key components of event-driven programming. (Select all that apply)

• A) Events

• B) Handlers

• C) Loops

• D) Listeners

Answer explanation

Event-driven programming relies on key components: A) Events trigger actions, B) Handlers define what to do when an event occurs, and D) Listeners wait for events to happen. C) Loops are not essential in this paradigm.

Which of the following is a tool used for GUI applications in event-driven programming?

• Tkinter

• Dash

• Flask

• Django

Answer explanation

Tkinter is a standard GUI toolkit for Python, specifically designed for creating event-driven applications. Unlike Dash, Flask, and Django, which are web frameworks, Tkinter is focused on desktop GUI development.

The role of the main loop in event-driven programming is to:

• handle events and dispatch them to the appropriate event handlers

• execute a sequence of instructions repeatedly

• manage memory allocation and deallocation

• perform input/output operations

Answer explanation

The main loop in event-driven programming is crucial for handling events as they occur and dispatching them to the correct event handlers, ensuring that the program responds appropriately to user actions and other events.

The code in Example 1 (Changing Label Text) demonstrates:

• how to create a basic window in tkinter

• how to handle events in tkinter

• how to use grid layout in tkinter

• how to close a window in tkinter

Answer explanation

The code in Example 1 illustrates how to create a basic window in tkinter, demonstrating the essential steps to initialize and display a window, making this the correct choice.

In Example 2, what is the purpose of the Entry widget in tkinter?

• To create a clickable button

• To display text

• To allow the user to enter text

• To create a dropdown menu

Answer explanation

The Entry widget in tkinter is specifically designed to allow the user to enter text. It provides a single-line text input field, making it ideal for user input, unlike buttons or dropdowns which serve different functions.

What does the function 'on_mouse_enter' do in TKinter code?

• It handles mouse click events.

• It handles mouse enter events.

• It handles keyboard events.

• It handles mouse exit events.

Answer explanation

The function 'on_mouse_enter' specifically handles mouse enter events, which occur when the mouse pointer enters a designated area. This makes 'It handles mouse enter events.' the correct choice.

To create a new Tkinter application, you would:

• Import the Tkinter module and create an instance of the Tk class

• Use the 'new Tkinter' command in the terminal

• Download the Tkinter application from the internet

• Write the application in HTML

Answer explanation

To create a Tkinter application, you need to import the Tkinter module and create an instance of the Tk class. This initializes the main window for your application, making it the correct first step.

To implement event handlers for button clicks in Tkinter, you would:

• Use the bind() method to associate a function with the button click event.

• Directly call the function without any association.

• Use the pack() method to handle button clicks.

• Implement a separate class for each button click.

Answer explanation

To handle button clicks in Tkinter, you should use the bind() method to associate a function with the button click event. This allows the function to be executed when the button is clicked, making it the correct choice.

The first step in creating a new Tkinter application for a basic calculator GUI is:

• Importing the Tkinter module

• Designing the calculator layout

• Writing the calculation logic

• Testing the application

Answer explanation

The first step in creating a Tkinter application is importing the Tkinter module. This is essential as it provides the necessary classes and functions to build the GUI for the calculator.