Why package your code?

• Share your code with others in a standardized way
• The user doesn’t have to bother about the internal structure of your code or where files are located
• Let tools like pip install your code and its dependencies automatically
• Make it easier to manage versions and updates of your code

What is a TOML anyway?

• It’s a simple configuration file format
• Provides settings and information in a structured and human-readable way
• TOML stands for “Tom’s Obvious, Minimal Language” (not important!)
• Not just Python, others like Rust, Jekyll, Julia, Hugo, Blender, etc. also use TOML for configuration files

TOML for Python

• In Python projects, we use a TOML file with a special name - pyproject.toml
• This file tells Python tools (like pip) how to build and distribute your package
• It contains metadata about your project: name, version, author, dependencies, etc.
• Think of it as an instruction manual for your project!

The minimum you need

Every Python package (nowadays) would have a pyproject.toml file. The absolute minimum you need is something like this:

[build-system]
requires = ["setuptools"]
build-backend = "setuptools.build_meta"

• This tells Python how to build your project
• setuptools is a tool that helps build and distribute Python packages
• Don’t worry too much about what all the terms here mean —- just know it’s required!

Adding project metadata

Now let’s add information about your project:

[build-system]
requires = ["setuptools"]
build-backend = "setuptools.build_meta"

[project]
name = "my-package"
version = "0.1.0"
description = "Generates signals, modifies them, and plots them"

The [project] section tells everyone what your project is called, what version it is, and what it does!

Adding authors and dependencies

You can specify who created the project:

[project]
name = "my-package"
version = "0.1.0"
description = "Generates signals, modifies them, and plots them"
authors = [
    {name = "Your Name", email = "you@example.com"}
]
dependencies = ["numpy", "pandas", "matplotlib"]

• authors is an array (a list) of objects. So, there can be multiple authors…

• When someone installs your package, pip will automatically install these dependencies too! :)

• You can also specify versions for your dependencies (e.g. numpy>=1.20)

Step 1: Create the file

• Navigate to your project’s root directory (the main folder of your project)
• Create a new file named pyproject.toml (exactly this name!)
• Open it in your text editor

Step 2: Add the build system

Start with the minimum:

[build-system]
requires = ["setuptools"]
build-backend = "setuptools.build_meta"

Copy this into your file and save it.

Step 3: Add project metadata

Add information about your project:

[project]
name = "give-a-sensible-name"
version = "0.1.0"
description = "Give an appropriate description of your project here!"
authors = [
    {name = "Your Name", email = "your.email@student.uni.nl"}
]
dependencies = ["what", "packages", "you-actually-use"]

Replace the placeholders with your actual information! For dependencies, only include packages that your code actually imports. If you’re not sure what you need, you can always add more later!

Step 5: Save and verify

Save your file as pyproject.toml in your project root. Your file structure should look like this:

my-awesome-project/
├── pyproject.toml
├── functions.py
├── script.py
└── plots/

That’s it! You’ve created your first pyproject.toml file!

Don’t forget the section headers!

❌ Wrong:

name = "my-package"
version = "0.1.0"

✅ Correct:

[project]
name = "my-package"
version = "0.1.0"

Without the section header, TOML doesn’t know where to put the information!

The file name is sacred

• It must be exactly pyproject.toml
• Not pyproject.txt
• Not pyproject-toml
• Not my_pyproject.toml
• Exactly. pyproject.toml.

You can always update it

• Don’t worry if you’re not sure about all the details
• Your pyproject.toml will grow as your project grows
• Add more metadata, dependencies, or configuration later