A guide to building a Python from scratch

Python is a versatile and powerful programming language, with a vast ecosystem of libraries and packages that make it a favourite among developers. If you've ever wanted to share your Python code with others or simplify your projects by creating reusable components, building a Python package is the way to go. In this tutorial, we'll take you through the process of building a Python package from scratch.

Why Build a Python Package?

Before we dive into the details of building a Python package, let's discuss why you might want to create one in the first place. Python packages serve several purposes-

Modularity: Packages allow you to organize your code into separate modules, making it more maintainable and readable.

Reusability: Once you've created a package, you can reuse it in multiple projects without duplicating code, saving time and effort.

Distribution: Sharing your code with others becomes straightforward. Python packages can be easily distributed via the Python Package Index (PyPI) or as source code.

Now, let's walk through the steps of building a Python package

Step 1: Set Up Your Project Structure

To start building your Python package, create a project directory and set up its basic structure. A typical package directory structure looks like this-

my_package/

my_module.py

README.md

LICENSE

setup.py

• py is where you'll define your Python code.
• md is a documentation file that describes your package and how to use it.
• LICENSE is an optional file to specify the licensing terms for your package.
• py is a Python script used for package distribution and installation.

Step 2: Write Your Python Code

In my_module.py, write the Python code you want to include in your package. For example, let's create a simple function that adds two numbers:

 def add_numbers(a, b):

    return a + b

Step 3: Write Package Metadata

In setup.py, you need to define some metadata about your package. This includes the package name, version, author, and more. Here's an example of a setup.py file:

from setuptools import setup

 setup(

    name="my_package",

    version="0.1",

    description="A simple Python package for adding numbers.",

    author="Your Name",

    author_email="your@email.com",

    url="https://github.com/yourusername/my_package",

    packages=["my_package"],

)

Step 4: Create a README

Write a README.md file that provides information on how to use your package, what it does, and any other relevant details. Good documentation is essential for users and potential contributors to understand your package.

Step 5: Choose a License

Choosing the right open-source license is crucial when sharing your code with the community. Common licenses include MIT, BSD, and GPL. You can find templates for different licenses online, and you can specify the license in your LICENSE file.

Step 6: Package Testing

Before sharing your package, it's essential to test it. Create a test directory and write test cases for your code. You can use Python testing libraries like unit test or pytest. Ensure that your code passes all tests.

Step 7: Build and Distribute Your Package

To create a distributable package, use the following commands:

python setup.py sdist bdist_wheel

This generates source distribution and wheel distribution files in a dist directory. You can then distribute your package by uploading it to the Python Package Index (PyPI) or by sharing the source code on GitHub or other code hosting platforms.

To upload to PyPI, make sure you have an account on PyPI. Then, install twine (if you haven't already) and use it to upload your package:

pip install twine

twine upload dist/*

Follow the prompts to enter your PyPI credentials and upload your package.

Step 8: Install Your Package

To test the installation of your package, create a virtual environment and install your package using pip:

python -m venv myenv

source myenv/bin/activate  # On Windows, use `myenv\Scripts\activate`

pip install my_package

You should now be able to import and use your package in Python scripts.

Conclusion

Building a Python package from scratch may seem like a daunting task, but it's a valuable skill for any Python developer. With a well-structured package, you can make your code more modular, reusable, and shareable. Whether you want to share your code with the world or simplify your own projects, creating a Python package is a great way to achieve those goals.

Hence, remember that good documentation and testing are essential for making your package user-friendly and reliable. With the steps outlined in this tutorial, you'll be well on your way to creating your Python package and contributing to the Python community. Happy coding!