WK4:Event-Driven Programming and IDE Features (Session 1)

• Programming
• Higher Education (degree)

Welcome to Week 4

Event-Driven Programming and IDE Features

Module Lecturer: Dr Raghav Kovvuri

Email: [e-mail]

Introduction

Definition: A programming paradigm where the flow of the program is determined by events

Events: User actions, sensor outputs, messages from other programs

Key Components

• Event Sources (e.g., UI elements, timers, network)
• Event Handlers (functions that respond to events)
• Event Loop (main program loop that listens for events)

Contrast with Sequential Programming:

• Sequential: Predetermined order of execution
• Event-Driven: Reactive, based on external inputs

Advantages of EDP

Scalability

Responsiveness 

Modularity

Resource Efficiency

Real-world Modeling

• Idle until events occur, conserving system resources
• Well-suited for GUI applications and I/O-bound programs

• Naturally models real-world interactions and processes
• Intuitive for developing simulations and interactive systems

• Quickly reacts to user inputs and system events
• Enhances user experience in interactive applications

• Easily handles multiple input sources
• Adaptable to complex user interfaces and multi-threaded environments

• Event handlers can be developed and maintained separately
• Facilitates parallel development in large projects

Example (Python & Tkinter) (1) 

 Basic Event-Driven Programming

• tk.Tk(): Creates the main window
• tk.Button(): Creates a button widget
• command=button_click: Associates the button click event with the handler
• root.mainloop(): Starts the event loop 

Key Concept: The program waits for user interaction rather than executing sequentially

Objects as Event Handlers:

• Methods of a class serve as event handlers
• Encapsulates behavior associated with events

State Management:

• Object's state can change in response to events
• Provides a natural way to model complex systems

Example (Python & Tkinter) (2) 

Objects as Event Sources:

• UI elements (buttons, text fields) as objects
• Each object can generate specific events

Combining OOP and Event-Driven Concepts:

Benefits:

• Improved code organization
• Easier state management
• Enhanced reusability and maintainability

Example: Simple Calculator GUI

• Download WK4_EDP_Calculator.py from Canvas and try to understand the Code 

Key Points:

• Class-based structure for organization
• Event handlers (click method) respond to button presses
• GUI layout managed within the class

Did you notice any issue with in the Output?

Hands on Exercise

Task: add a reset input button to the calculator. This button should clear the current input and reset the calculator to its initial state.

IDE Features

Setup and learn basics of VS Code

Using extensions in VS Code

Debugging

Version Control in VS Code

Version Control in VS Code

Version Control in VS Code

Version Control in VS Code

Version Control in VS Code

https://code.visualstudio.com/docs/getstarted/introvideos

For Introductory Videos Visit

Conclusion

• We've evolved our OOP calculator to use event-driven programming
• Core OOP principles remain the same
• Event-driven approach makes our program more interactive
• This is how most modern GUI applications work! 

Additional Resources

Tkinter documentation: https://docs.python.org/3/library/tkinter.html

Real Python's Tkinter tutorial: https://realpython.com/python-gui-tkinter/

VS Code Python tutorial: https://code.visualstudio.com/docs/python/python-tutorial