How does meson-python work?#

Old documentation

You are looking at the old documentation. We are currently in the process of refactoring the whole documentation and this page was part of the old version. While it still contains lots of relevant information, it is not necessarily in the format we ultimately want to present, and is not well integrated with the other parts of the documentation.

How does it work?#

We implement the Python build system hooks, enabling any standards compliant Python tool (pip, pypa/build, etc.) to build and install the project.

meson-python will build a Python sdist (source distribution) or wheel (binary distribution) from Meson project.

Source distribution (sdist)#

The source distribution is based on meson dist, so make sure all your files are included there. In git projects, Meson will not include files that are not checked into git, keep that in mind when developing. By default, all files under version control will be included in the sdist. In order to exclude files, use export-ignore or export-subst attributes in .gitattributes (see the git-archive documentation for details; meson dist uses git-archive under the hood).

Local (uncommitted) changes to files that are under version control will be included. This is often needed when applying patches, e.g. for build issues found during packaging, to work around test failures, to amend the license for vendored components in wheels, etc.

Binary distribution (wheels)#

The binary distribution is built by running Meson and introspecting the build and trying to map the files to their correct location. Due to some limitations and/or bugs in Meson, we might not be able to map some of the files with certainty. In these cases, we will take the safest approach and warn the user. In some cases, we might need to resort to heuristics to perform the mapping, similarly, the user will be warned. These warnings are not necessarily a reason for concern, they are there to help identifying issues. In these cases, we recommend that you check if the files in question were indeed mapped to the expected place, and open a bug report if they weren’t.

If the project itself includes shared libraries that are needed by other files, those libraries will be included in the wheel, and native files will have their library search path extended to include the directory where the libraries are placed.

If the project depends on external shared libraries, those libraries will not be included in the wheel. This can be handled in several ways by the package developer using meson-python:

  1. Finding or creating a suitable Python package that provides those shared libraries and can be added to dependencies in pyproject.toml.

  2. Vendoring those libraries into the wheel. Currently meson-python does not provide an OS-agnostic way of doing that; on Linux auditwheel can be used, and on macOS delocate. Or, the package developer can copy the shared libraries into the source tree and patch files to include them.

  3. Documenting that the dependency is assumed to already be installed on the end user’s system, and letting the end user install it themselves (e.g., through their Linux distro package manager).