Python: Project Management

There are several ways to manage dependencies and project metadata in Python. While they differ in their syntax and capabilities, they can all be used to specify the dependencies required for a Python project.

pyproject.toml

pyproject.toml is a configuration file used in modern Python projects to specify various aspects of the project, including its dependencies, build settings, and package metadata. It is part of the Python Packaging ecosystem, which provides a standardized way to manage Python packages and their distribution.

pyproject.toml is similar to Project.toml, used in Julia projects.

pyproject.toml is used by the Poetry package manager, a popular tool for managing dependencies and building Python projects. Poetry relies on the pyproject.toml file to define the project’s dependencies, and uses this information to create a virtual environment for the project and install the necessary dependencies.

It provides a simple, declarative way to manage project dependencies, without the need for separate requirements.txt or setup.py files. It also allows developers to specify other project metadata, such as its version number, author, and license.

With pep-0621 pyproject.toml is the standard for managing Python projects, and increasingly used by many popular Python packages and tools.

By adopting pyproject.toml and the Python Packaging ecosystem, developers ensure that their projects are well-organized, maintainable, and easily sharable with others in the Python community.

Poetry

Poetry is a modern Python packaging and dependency management tool that helps simplify the process of managing dependencies and building projects. It allows developers to define their project dependencies in a declarative way using a simple pyproject.toml file, rather than relying on separate requirements.txt or setup.py files.

One of the key advantages of using Poetry is that it provides a streamlined workflow for managing dependencies and virtual environments. It can automatically create and manage virtual environments for each project, isolating project dependencies and avoiding conflicts with system-level packages. Poetry also provides powerful tools for managing dependencies, including automatic dependency resolution, dependency locking, and the ability to publish and install packages from both PyPI and private repositories.

Another advantage of using Poetry is that it provides a simple, consistent interface for managing all aspects of a Python project, from dependency management to building and publishing packages. This makes it easier for developers to focus on writing code and building their projects, without getting bogged down in the details of project management.

Legacy Project Management

Although pyproject.toml is the new standard for managing dependencies and metadata in modern Python projects, you may still encounter older projects that use requirements.txt and setup.py.

requirements.txt is a file used to specify a project’s dependencies in a simple, text-based format. Each line in the file lists a package name and version number, separated by an equals sign. This format is easy to read and edit, and is supported by many Python tools and frameworks. However, it lacks some of the advanced features provided by pyproject.toml, such as the ability to specify package metadata and build settings.

setup.py is a script used to build and distribute Python packages. It includes metadata about the package, such as its name, version, and author information, as well as instructions for building and installing the package. Although setup.py is still used in many projects, it has some limitations, such as the inability to specify dependencies with the same level of detail as pyproject.toml.

Recommendations

If you’re starting a new Python project from scratch, it’s generally not recommended to use requirements.txt or setup.py as the primary method for managing dependencies and metadata. Instead, you should use pyproject.toml, which is the modern standard for these tasks.

However, if you’re working with an existing project that uses requirements.txt or setup.py, it’s often necessary to keep these files around for compatibility reasons. For example, if you’re working on a project that is already deployed to production and relies on requirements.txt to specify its dependencies, you may not want to switch to pyproject.toml right away, since this could cause compatibility issues or require a significant amount of testing.