Re-using code is key to writing maintainable and correct code. We already learnt how to package code into functions. Now we learn how to package functions into modules.
We will also talk about objects because everything in Python is an “object”. Objects are a more general approach to “packaging code into re-usable units”.
Modules
Modules and packages are “libraries” for Python code. You will use them constantly to use existing code or to re-use your own code.
When working with notebooks it is especially useful to modularize tested code outside the notebook and then only import your module in the notebook.
Objects
Objects (created in Python with the class statement, and hence often also called classes) combine data and code into a single unit. An object contains data (held in variables that are called attributes) and it also contains functions (called methods) that know how to operate on the data in the object.
Python is an object oriented (OO) language and objects are everywhere — in fact everything is an object in Python so anything you lear about objects applies to everything in Python.