A PEP 517 backend for PDM that supports PEP 621 metadata

# PDM-PEP517

Yet another PEP 517 backend.

This is the backend for PDM projects, while you can also use it alone. It reads the metadata of PEP 621 format and coverts it to Core metadata.

## Use as PEP 517 build backend

Edit your pyproject.toml as follows:

[build-system]
requires = ["pdm-pep517"]
build-backend = "pdm.pep517.api"


## Tool specific settings

Besides of the standard fields specified in PEP 621, PDM-PEP517 honors some other settings to change the build behavior. They should be defined under [tool.pdm.build] table:

[tool.pdm.build]
# Specify where the Python packages live.
package-dir = "src"
# File patterns to include, the paths are relative to the project root.
includes = []
# File patterns to exclude, the paths are relative to the project root.
excludes = []
# File patterns to include in source distribution and exclude in wheel distribution.
source-includes = []
# An extra script to populate the arguments of setup(), one can build C extensions with this script. Or a custom build() function to generate files.
setup-script = "build.py"
# If true, the setup-script will run in a generated setup.py file.
run-setuptools = false
# Override the Is-Purelib value in the wheel.
is-purelib = true
# Change the editable-backend: path(default) or editables
editable-backend = "editables"


You don't have to specify all of them, PDM-PEP517 can also derive these fields smartly, based on some best practices of Python packaging.

## Dynamic project version

pdm-pep517 can also determine the version of the project dynamically. To do this, you need to leave the version field out from your pyproject.toml and add dynamic = ["version"]:

[project]
...
- version = "0.1.0" remove this line
+ dynamic = ["version"]


Then in [tool.pdm.version] table, specify how to get the version info. There are two ways supported:

1. Read from a static string in the given file path:
[tool.pdm.version]
source = "file"
path = "mypackage/__init__.py"


In this way, the file MUST contain a line like:

__version__ = "0.1.0" # Single quotes and double quotes are both OK, comments are allowed.

1. Read from SCM tag, supporting git and hg:
[tool.pdm.version]
source = "scm"


When building from a source tree where SCM is not available, you can use the env var PDM_PEP517_SCM_VERSION to pretend the version is set.

PDM_PEP517_SCM_VERSION=0.1.0 python -m build


## Writing SCM version to file

You can instruct PDM-PEP517 to write back the dynamic version fetched from SCM to a file:

[tool.pdm.version]
source = "scm"
write_to = "foo/version.txt"


By default, PDM-PEP517 will just write the SCM version itself. You can provide a template as a Python-formatted string to create a syntactically correct Python assignment:

[tool.pdm.version]
source = "scm"
write_to = "foo/_version.py"
write_template = "__version__ = '{}'"


Note that PDM-PEP517 will rewrite the whole file each time, so you can't have additional contents in that file.

## Custom Build Script

With custom build script, you can call other tools to generates files to be included in the wheel. Just set the setup-script field under [tool.pdm.build] table to the path of the script.

In the script, you expose a function named build, which takes two arguments:

• src(str): the path of the source directory
• dst(str): the path of the destination directory

Example:

def build(src, dst):
with open(os.path.join(dst, "myfile.txt"), "w") as f:
# Put a file in the wheel
f.write("Hello World!")


Note that the generated file hierarchy will be preserved in the wheel: $dst/myfile.txt -> $wheel_root/myfile.txt.

When run-setuptools is true, the build function will be called in a generated setup.py file, with the setup parameters as the only argument.

Example:

def build(setup_params):
# add ext_modules to the setup() arguments
setup_parms.update(ext_modules=[Extension("myextension", ["myextension.c"])])


The will result in a setup() call like following:

setup(
name="mypackage",
ext_modules=[Extension("myextension", ["myextension.c"])],
)


By default, when setup-script is set, the resulted wheel will be platform-specific, but you can override this behavior by setting is-purelib to false

## Supported config settings

pdm-pep517 allows passing config_settings to modify the build behavior. It use the same option convention as python setup.py bdist_wheel.

--python-tag
Override the python implementation compatibility tag(e.g. cp37, py3, pp3)
--py-limited-api
Python tag (cp32|cp33|cpNN) for abi3 wheel tag
--plat-name
Override the platform name(e.g. win_amd64, manylinux2010_x86_64)


For example, you can supply these options with build:

python -m build --sdist --wheel --outdir dist/ --config-setting="--python-tag=cp37" --config-setting="--plat-name=win_amd64"


pip doesn't support passing config_settings yet, please stick to build as the recommended frontend.

## Project details

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