Functions and Reusable Logic

The project

In the previous lesson, you built a smart thermostat that decided whether to turn on the fan, heater, or AC depending on the temperature, season, and whether it was peak hours. But here’s the challenge: right now, your code works for only one room at a time.

What if you want to check the comfort level in the living room, bedroom, and kitchen, each with different temperatures? And what if you want the same room to adjust its temperature based on who is there at that moment?

Copy-pasting the same decision logic again and again is messy, error-prone, and hard to update. Instead, Python gives us a superpower: you can define your own functions.

The programming concept

Remember how the built-in functions print() and input() feel like little magic boxes that do something when you call them? Of course, a programmer at Python’s headquarters—or more likely, part of the global developer community—had to define those functions so you could use them. But what if you could create your own? After all, no programming language can possibly include every function anyone might ever need, already packaged and ready to go. For instance, do you really think there would ever be a ...