Software Design Principles: Applying KISS and YAGNI with a Real Python Example

Introduction Applying design principles in software development helps create cleaner, more efficient, and easier-to-maintain systems. This article introduces two essential principles —KISS and YAGNI— using a real-world example written in Python. The goal is to demonstrate how to write focused and effective code from the beginning without overengineering. What is KISS? KISS stands for "Keep It Simple, Stupid". This principle encourages developers to keep their code as simple as possible. Simpler code is easier to read, debug, maintain, and extend when needed. What is YAGNI? YAGNI means "You Aren’t Gonna Need It". It reminds developers to avoid building features based on hypothetical future needs. Instead, focus on writing only what is needed today, not what might be useful someday. Python Code Example tasks = [] def add_task(description): tasks.append({"description": description, "done": False}) def list_tasks(): for i, task in enumerate(tasks, 1): status = "✔" if task["done"] else "✘" print(f"{i}. [{status}] {task['description']}") def complete_task(index): if 0

Apr 30, 2025 - 23:44

Software Design Principles: Applying KISS and YAGNI with a Real Python Example

Introduction

Applying design principles in software development helps create cleaner, more efficient, and easier-to-maintain systems. This article introduces two essential principles —KISS and YAGNI— using a real-world example written in Python. The goal is to demonstrate how to write focused and effective code from the beginning without overengineering.

What is KISS?

KISS stands for "Keep It Simple, Stupid". This principle encourages developers to keep their code as simple as possible. Simpler code is easier to read, debug, maintain, and extend when needed.

What is YAGNI?

YAGNI means "You Aren’t Gonna Need It". It reminds developers to avoid building features based on hypothetical future needs. Instead, focus on writing only what is needed today, not what might be useful someday.

Python Code Example

tasks = []

def add_task(description):
    tasks.append({"description": description, "done": False})

def list_tasks():
    for i, task in enumerate(tasks, 1):
        status = "✔" if task["done"] else "✘"
        print(f"{i}. [{status}] {task['description']}")

def complete_task(index):
    if 0 < index <= len(tasks):
        tasks[index - 1]["done"] = True

# Example usage:
add_task("Finish article for Dev.to")
add_task("Record explanation video")
list_tasks()
complete_task(1)
list_tasks()

Code Explanation

tasks = []: initializes an empty list to hold task entries.

add_task(description): appends a dictionary with task description and a default “not done” status.

list_tasks(): displays each task with its number, a checkmark (✔) if completed or ✘ if not, and the description.

complete_task(index): updates the selected task's status to completed based on the index provided.

The last lines show a usage example: adding tasks, listing them, completing one, and listing again to see the updated state.

Conclusion

This example shows that simple, readable code can effectively solve real problems without overcomplication. By following KISS and YAGNI, developers can produce working solutions that are easy to maintain and evolve later, if truly needed.