setuptoolsscm

setuptoolsscm is a command-line utility that is part of the setuptools library in Python. Its primary function is to interact with version control systems to determine the current version of a package. When a Python package is being built or installed, setuptools often needs to know its version number. If the package is under version control, setuptoolsscm can query the system (such as Git or Mercurial) to extract this information automatically, rather than requiring it to be explicitly defined in the setup script.

This automation helps in maintaining consistent versioning between the code repository and the distributed package. It allows developers to avoid manually updating version numbers in multiple places. The utility works by looking for specific version markers or tags within the version control history. When setuptools invokes setuptoolsscm during the build process, it checks for a clean working directory and specific commit tags that indicate a release. If these conditions are met, it can derive the version string. This is particularly useful for packages that are still under active development, as it can provide a more precise version based on the commit history. It's a behind-the-scenes tool that contributes to streamlined package management in the Python ecosystem.