pep517

API to call PEP 517 hooks

.. warning::

The core of this package has been renamed to pyproject-hooks <https://pyproject-hooks.readthedocs.io/>. Please use that package (low level) or build <https://pypa-build.readthedocs.io/en/stable/> (higher level) in place of pep517.

PEP 517 <https://www.python.org/dev/peps/pep-0517/>_ specifies a standard API for systems which build Python packages.

PEP 660 <https://www.python.org/dev/peps/pep-0660/>_ extends it with a build mode that leads to editable installs.

This package contains wrappers around the hooks specified by PEP 517 and PEP 660. It provides:

• A mechanism to call the hooks in a subprocess, so they are isolated from the current process.
• Fallbacks for the optional hooks, so that frontends can call the hooks without checking which are defined.

Run the tests with pytest or tox <https://pypi.org/project/tox>_.

Usage—you are responsible for ensuring build requirements are available:

.. code-block:: python

import os
import tomli
from pep517.wrappers import Pep517HookCaller

src = 'path/to/source'  # Folder containing 'pyproject.toml'
with open(os.path.join(src, 'pyproject.toml'), 'rb') as f:
    build_sys = tomli.load(f)['build-system']

print(build_sys['requires'])  # List of static requirements
# The caller is responsible for installing these and running the hooks in
# an environment where they are available.

hooks = Pep517HookCaller(
    src,
    build_backend=build_sys['build-backend'],
    backend_path=build_sys.get('backend-path'),
)

config_options = {}   # Optional parameters for backend
# List of dynamic requirements:
print(hooks.get_requires_for_build_wheel(config_options))
# Again, the caller is responsible for installing these build requirements

destination = 'also/a/folder'
whl_filename = hooks.build_wheel(destination, config_options)
assert os.path.isfile(os.path.join(destination, whl_filename))

Deprecated high-level

For now, pep517 also contains higher-level functions which install the build dependencies into a temporary environment and build a wheel/sdist using them. This is a rough implementation, e.g. it does not do proper build isolation. The PyPA build project <https://github.com/pypa/build>_ is recommended as an alternative, although it's still quite young in October 2020. This layer of functionality in pep517 is now deprecated, but won't be removed for some time, as there is code relying on it.

High level usage, with build requirements handled:

.. code-block:: python

import os
from pep517.envbuild import build_wheel, build_sdist

src = 'path/to/source'  # Folder containing 'pyproject.toml'
destination = 'also/a/folder'
whl_filename = build_wheel(src, destination)
assert os.path.isfile(os.path.join(destination, whl_filename))

targz_filename = build_sdist(src, destination)
assert os.path.isfile(os.path.join(destination, targz_filename))

To test the build backend for a project, run in a system shell:

.. code-block:: shell

python3 -m pep517.check path/to/source  # source dir containing pyproject.toml

To build a backend into source and/or binary distributions, run in a shell:

.. code-block:: shell

python -m pep517.build path/to/source  # source dir containing pyproject.toml

All of this high-level functionality is deprecated.