Getting Started with Python: Creating a Hello World Project Using Poetry

Introduction

Poetry is a powerful dependency management and packaging tool for Python. It simplifies project creation, dependency installation, and environment isolation. In this tutorial, we’ll walk through the steps to create and initialize a “Hello, World!” Python project using Poetry.

Prerequisites

Before we start, make sure you have the following installed on your system:

1. Python (version 3.7 or later)
2. Poetry (follow the official installation guide)

You can verify your installations by running:

python --version
poetry --version

Step 1: Create a New Project

Start by creating a new directory for your project. Navigate to the directory where you want to store your project and run:

poetry new hello-world

This command creates a new folder named hello-world with the following structure:

hello-world/
├── README.rst
├── hello_world
│   └── __init__.py
├── pyproject.toml
└── tests
    ├── __init__.py
    └── test_hello_world.py

Key Components

• hello_world/: Contains your Python package.
• pyproject.toml: Defines your project dependencies and metadata.
• tests/: Directory for your test cases.

Step 2: Add a “Hello, World!” Script

Navigate to the hello_world directory:

cd hello-world/hello_world

Edit the __init__.py file or create a new file, main.py:

# hello_world/main.py
def main():
    print("Hello, World!")

if __name__ == "__main__":
    main()

Step 3: Update pyproject.toml

Ensure the pyproject.toml file includes an entry point so you can run the script as a command. Add the following under the [tool.poetry.scripts] section:

[tool.poetry.scripts]
hello-world = "hello_world.main:main"

Step 4: Install Dependencies

Run the following command to install any dependencies and prepare the environment:

poetry install

Step 5: Run Your Script

To test your script, use:

poetry run hello-world

You should see the output:

Hello, World!

Step 6: Adding Tests

To ensure your script works correctly, add a test case in the tests/test_hello_world.py file:

def test_main(capsys):
    from hello_world.main import main

    main()
    captured = capsys.readouterr()
    assert captured.out == "Hello, World!n"

Run the tests using Poetry:

poetry run pytest

Conclusion

Congratulations! You’ve successfully created a “Hello, World!” Python project using Poetry. This setup provides a solid foundation for building more complex applications while managing dependencies and packaging effortlessly.

Feel free to explore additional features of Poetry, like dependency version constraints, virtual environments, and publishing packages.