When you distribute your Python package, it is essential to specify which external packages your code depends on. This process is called dependency specification, and it is managed within your pyproject.toml file. By declaring dependencies, you ensure that anyone installing your package will automatically receive all the required libraries, preventing runtime errors due to missing modules. This approach also helps maintain reproducibility, as it makes clear which versions of dependencies your package was tested with, reducing the risk of incompatibilities.

Neglecting to specify dependencies can lead to frustrating user experiences. If users have to guess or manually install the correct versions of required libraries, they may encounter unexpected failures. Proper dependency management also allows tools like pip to resolve and install dependencies efficiently, streamlining the installation process for your package.

[project]
name = "my_cool_package"
version = "0.1.0"
description = "A sample package demonstrating dependency management"
authors = [
    { name="Your Name", email="your.email@example.com" }
]

dependencies = [
    "pandas-datareader>=0.10.0",
    "scikit-learn>=1.2.2,<2.0.0",
    "matplotlib>=3.10.3"
]