♻️ Reuse, Reduce, Recycle

✏️ Section undergoing re-write. Come back soon.

You and your friends want to go out and do something fun, but none of you can agree on what to do. To help you make a decision, you decide to write a computer program that will make the decision for you.

You create a file named decision.py, and add the following lines:

activities = [
    "Boardgame Cafe",
    "Movies",
    "Roller skating",
    "Video Games",
    "Karaoke",
    "Amusement Park"
]

You don't have to write everything from scratch, you can reuse code that other people have written.

Python is a batteries-included language; when you downloaded the interpreter, you also downloaded a lot of extra files of code for you to freely reuse. These code files are collectively called the standard library. You can read more about it at the Python Standard Library documentation page.

Python modules and packages

We call a particular bundle of functionality a packages. For example, there is a standard library module for generating random numbers called random. You use it like this:

import random

# Prints a random integer from 1 to 10
print(random.randint(1, 10))

Packages are composed of many Python modules. A module is a single Python file like myfile.py

Conflict with stdlib

When you write your own modules, don't name them after modules found in the standard library. For example, if you have a module that does something with HTML you might be tempted to call it html.py But there already exists an html module in the stdlib.

If you import a library that uses the stdlib html, it will throw an error because the Python interpreter will accidentally try to use your html.py. Chances are you haven't written all the code that it's in the stdlib html module, so your code will throw an error.

🏋️ Exercises