Building modules in Python

So recently I’ve been involved in a lot more development work as a result of changing direction in my career. And honestly it’s been really interesting. Most recently I’ve been doing a lot of work with Python, which up until now was a language that I was familiar with but hadn’t done much with.

And I have to tell you, I’ve really been enjoying it. Python really is a powerful language in it’s flexibility, and I’ve been doing a lot of work with building out scripts to do a variety of tasks.

As mentioned in previous blog posts, I’m a big fan of DevOps and one of the things I try to embrace quickly is the idea of packaging code to maximize re-use. And to that end, I recently took a step back and went through how to build python modules, and how to package them up for using a pip install.

How to structure your Python Modules?

The first thing I’ve learned about Python is that it very much focused on the idea of convention. And what I mean by that is that Python focuses on the idea of using convention to define how things are done over have a rigid structure that requires configuration. And putting together these kinds of modules is no different.

So when you go through the setting up of the configuration, you would use the following structure:

• {Project Folder}
  • {Module Folder}
  • __init__.py
  • {Module Code}
• setup.py
• requirements.txt

From there the next important part of the setup is to create a setup.py. As you start to flush this out, you are going to be identifying all the details of your package here along with dependencies that you want pip to resolve. A great post on project structure is here.

import setuptools 

with open("README.md", "r") as fh: 
    long_description = fh.read() 

setuptools.setup( 
    name="kevin_module", 
    version="1.0.0", 
    python_requires = '>=3.7',
    packages = setuptools.find_packages(),
    author="...", 
    author_email="...", 
    description="...", 
    long_description=long_description, 
    long_description_content_type="text/markdown", 
    license="MIT", 
) 

And next is the requirement for a readme.md, which will outline the specifics of your package. This where you are going to put the documentation.

Next the important part is how to implement the __init__.py, this is important and is basically a manifest for the namespace of the library. Below is the sample.

from .{python code file} import {class}

From there you can actually use a utility called twine to bundle the package, and information on twine can be found here. Below is the command to create the bundle. There is a great post on that found here.