setuptools vs Spack

setuptools is a free Python packaging library for preparing projects for sharing and installation. It can serve as a project build backend, discover packages and namespaces, and let maintainers control which packages are distributed. It handles build-system requirements plus required and optional dependencies, including version limits and environment markers, and supports dependency groups. Configured entry points can generate console-command and plugin scripts during installation. Editable installs apply source changes without rebuilding and reinstalling. The library can build C and C++ extension modules, and its documentation covers workflows with pip, build, and PyPI. Setuptools runs on Linux, macOS, and Windows, while the current PyPI listing requires Python 3.10 or later. The project identifies modern PyPA-standard APIs and documented customization APIs as its most stable interfaces. It is free, has no free trial, and professional support is available through a Tidelift Subscription.

Spack is a package manager for installing scientific software on supercomputers, Linux, macOS, and Windows. It is designed for large supercomputing centers that share software across clusters and varied architectures, and is available at free. Users can choose package versions, compiler choices, target architectures, and compile-time options, while controlling direct and transitive dependencies. Spack can build stacks that combine Python or R packages with C, C++, or Fortran libraries. Each distinct package and dependency configuration receives its own prefix, so different builds can coexist without a new installation disrupting an existing one. Software can be installed to a user-selected directory without administrator privileges. Spack primarily builds customized software from source and also supports binary installation through build caches. It supports lockfiles, environment management, and private registries. Package recipes are Python scripts, and the `spack create` command generates starter boilerplate. The project is distributed under either the MIT license or Apache License 2.0, at the user's option.