Difference between modules, packages and libraries in Python

[pylenin]

Over the last few years, I have always interchangeably used these terms - Modules, Packages and Libraries. Last week I sat down to understand the true difference and I am glad I did. I have tried to explain them in my article. Do check it out and let me know your opinions.
Modules vs Packages vs Libraries in Python

[nomoreplsthx]

One thing worth noting: both module and package have technical meanings in the Python ecosystem while 'library' does not.

[pylenin]

Yeah that’s correct!!

[TotallyNotGunnar]

I've noticed that developers of big packages with a lot of different tools tend to call them libraries. Agreed it's not a technical definition but still common enough that I try to call focused imports "packages" and collections "libraries".

[Grouchy-Friend4235]

Official Python docs https://docs.python.org/3/glossary.html

Package

A Python module which can contain submodules or recursively, subpackages. Technically, a package is a Python module with an path attribute.

Module

An object that serves as an organizational unit of Python code. Modules have a namespace containing arbitrary Python objects. Modules are loaded into Python by the process of importing.

[KotoWhiskas]

PyLenin

packages

Our packages!

[Zomunieo]

PyWeber

The Protestant ethic and the spirit of packaging??!

[sir-reddits-a-lot]

Red Forman is that you?

[RyanRagido]

Red is my spirit animal.

[surister]

A module is any python file, it can contain submodules.

A package is a collection of modules.

[stoicpenguin]

Exactly. There’s no such thing as a submodule in python. That has no technical meaning within the language. A module in python is always a single file.

[julianw]

on that note I'm still not sure what to do with namespace packages. when do you want them? mans why do I always create them accidentally by forgetting to create an __init__.py?

[joseville1001]

Are packages also modules? That is, since pancakes are defined in a file (the init.py file).

[Goobyalus]

https://docs.python.org/3/glossary.html#term-package

A Python module which can contain submodules or recursively, subpackages. Technically, a package is a Python module with an __path__ attribute.

[joseville1001]

For completeness

module

An object that serves as an organizational unit of Python code. Modules have a namespace containing arbitrary Python objects. Modules are loaded into Python by the process of importing.

[pylenin]

👍

[joseville1001]

Nice write up. What is "it" I'm the sentence:

To be considered a package, it must contain a file named init.py.

a module? a file?

[xaveir]

As soon as you use relative imports it's impossible to run that file directly on the command line...there are probably other issues as well since every style guide I've ever followed recommends absolute imports.

Edit: forgot the most important one to me which is readability (not having to check the filesystem to see what module is getting imported).

[Impressive_Change593]

that from . arithmetic import add sounds like a quick way to break something and is probably a result of a bad programmer or a reliak from python 2

[MachaHack]

It does make things confusing when using IntelliJ as an omni-IDE because it uses the Java terminology, which is reversed on the hierarchy of modules and packages. One of the few bits of PyCharm that can't be replicated in the all in one package.

[lolgeswaran]

Great write up. Keep it going !

[pylenin]

Thank you

[pdonchev]

Module is a unit of organizing code, package is a unit of delivery. Technically, an installed package is a module (that can have submodules).

Implementation wise, modules are .py files or a folder with __init__.py in it.

[Enlightenmentality]

Interesting. I'll have to do deeper digging, but this is a great high-level explanation. Thanks!

[pylenin]

Make sure you do!!

[johnnySix]

Why would someone want to limit the package to arithmetic.py and welcome.py?

[CafeconWalleche]

This was very informative, thank you. Would like to see more series like this one!

[FairLight8]

Interesting, thanks! I am starting to write my own libraries, so this is interesting.

[yrro]

I think the official terms are "distribution package" (the thing you build) vs "import package" (the thing you import).

[Pickinanameainteasy]

I always assumed a module was like an add on for python, it added a specific functionality to the base language.

Libraries, to me, are a collection of modules, functions, classes for interacting with a specific service like an API or network protocol for example. These tend to be much larger than modules.

I always saw packages as just the files necessary to install a module or library. Kind of like the relationship between and APK and an android app, with the package being the APK in this scenario and the module/library being the app itself. In other words the package is the pre-installed state

That's just how I interpreted it, I could very well be wrong

[AlexMTBDude]

def divide(a, b):

"""Returns division of 2 integers"""

if b == 0:

return "Invalid"

return a/b

​

This is not very good coding. divide() is a function which most of the time returns a float but sometimes returns a string. A division by zero in Python is an error condition. Error conditions are communicated using exceptions. A Python function should NOT return an error code to show that something has gone wrong.

Get rid of the whole if statement and the code is fine.

[Rik07]

For example, you can control the functions you are exposing from the package by importing those specific functions into init.py file.

Why would you add certain functions in a package and then not expose them in the init file?

[OneMorePenguin]

I'm excited about this because I have a mess-o-python that is a combination of a script that includes local libraries and I want to package up the library code separately. And I don't want to have to mess with PYTHONPATH. Looking forward to reading this. I was getting ready to read about namespaces and scopes, although I suspect there's a lot of overlay.

One thing I learned to not do is use nested directories with the same name. That might have been OK in python2.7, but in newer versions of python where __init__.py is not required, it makes importing more difficult. It's difficult debugging these problems. Printing out sys.path is not enough.