Modernise setup scripts

.github/workflows/ci-wheels.yml

@@ -132,7 +132,7 @@ jobs:
     name: "Publish to Test PyPI"
     runs-on: ubuntu-latest
     # upload to Test PyPI for every commit on main branch
-    if: github.event_name == 'push' && github.event.ref == 'refs/heads/main'
+    if: github.event_name == 'push'
     steps:
     - uses: actions/download-artifact@v3
       with:

cf_units/tests/test_coding_standards.py

@@ -128,7 +128,6 @@ def test_python_versions():
 
     # Places that are checked:
     pyproject_toml_file = REPO_DIR / "pyproject.toml"
-    setup_cfg_file = REPO_DIR / "setup.cfg"
     tox_file = REPO_DIR / "tox.ini"
     ci_locks_file = workflows_dir / "ci-locks.yml"
     ci_tests_file = workflows_dir / "ci-tests.yml"
@@ -137,19 +136,19 @@ def test_python_versions():
     text_searches: list[tuple[Path, str]] = [
         (
             pyproject_toml_file,
-            "target-version = ["
-            + ", ".join([f'"py{p}"' for p in supported_strip])
-            + "]",
-        ),
-        (
-            setup_cfg_file,
             "\n    ".join(
                 [
-                    f"Programming Language :: Python :: {ver}"
+                    f'"Programming Language :: Python :: {ver}",'
                     for ver in supported
                 ]
             ),
         ),
+        (
+            pyproject_toml_file,
+            "target-version = ["
+            + ", ".join([f'"py{p}"' for p in supported_strip])
+            + "]",
+        ),
         (
             tox_file,
             "[testenv:py{" + ",".join(supported_strip) + "}-lock]",

pyproject.toml

@@ -5,11 +5,70 @@ requires = [
   "setuptools_scm[toml]>=7.0",
   "wheel",
   "oldest-supported-numpy",
-  "Cython>=3.0"
+  "Cython>=3.0",
 ]
 # Defined by PEP 517
 build-backend = "setuptools.build_meta"
 
+[project]
+name = "cf-units"
+authors = [
+    {name = "cf-units Contributors", email = "scitools.pub@gmail.com"}
+]
+classifiers = [
+    "Development Status :: 5 - Production/Stable",
+    "Intended Audience :: Science/Research",
+    "License :: OSI Approved :: BSD License",
+    "Operating System :: OS Independent",
+    "Programming Language :: Python",
+    "Programming Language :: Python :: 3 :: Only",
+    "Programming Language :: Python :: 3.10",
+    "Programming Language :: Python :: 3.11",
+    "Programming Language :: Python :: 3.12",
+    "Programming Language :: Python :: Implementation :: CPython",
+    "Topic :: Scientific/Engineering",
+    "Topic :: Scientific/Engineering :: Atmospheric Science",
+    "Topic :: Scientific/Engineering :: Oceanography",
+]
+dependencies = [
+    "antlr4-python3-runtime ==4.11.1",   # To update this, see cf_units/_udunits2_parser/README.md
+    "cftime >=1.2",
+    "jinja2",
+    "numpy ==1.26.4"
+    # udunits2 cannot be installed with pip, and it is expected to be
+    #  installed separately.
+]
+description = "Units of measure as required by the Climate and Forecast (CF) metadata conventions"
+dynamic = [
+    "version",
+]
+keywords = [
+    "units",
+    "cf",
+    "cf-metadata",
+    "netcdf",
+    "science",
+    "earth-science",
+    "oceanography",
+    "meteorology",
+    "climate",
+    "python",
+]
+license.file = "LICENSE"
+readme = "README.md"
+requires-python = ">=3.9"
+
+[project.optional-dependencies]
+docs = ["sphinx"]
+test = ["codecov", "cython", "jinja2", "pip", "pytest", "pytest-cov"]
+all = ["pre-commit", "sphinx", "codecov", "cython", "jinja2", "pip", "pytest", "pytest-cov"]
+
+[project.urls]
+Code = "https://github.com/SciTools/cf-units"
+Discussions = "https://github.com/SciTools/cf-units/discussions"
+Issues = "https://github.com/SciTools/cf-units/issues"
+Documentation = "https://cf-units.readthedocs.io"
+
 [tool.coverage.run]
 branch = true
 plugins = [
@@ -41,6 +100,12 @@ doctest_optionflags = "NORMALIZE_WHITESPACE ELLIPSIS NUMBER"
 minversion = "6.0"
 testpaths = "cf_units"
 
+[tool.setuptools]
+license-files = ["LICENSE"]
+
+[tool.setuptools.packages.find]
+include = ["cf_units"]
+
 [tool.setuptools_scm]
 write_to = "cf_units/_version.py"
 local_scheme = "dirty-tag"

setup.cfg

@@ -1,66 +1,3 @@
-[metadata]
-author = SciTools Developers
-classifiers =
-    Development Status :: 5 - Production/Stable
-    Intended Audience :: Science/Research
-    License :: OSI Approved :: BSD License
-    Operating System :: OS Independent
-    Programming Language :: Python :: 3 :: Only
-    Programming Language :: Python :: 3.10
-    Programming Language :: Python :: 3.11
-    Programming Language :: Python :: 3.12
-    Topic :: Scientific/Engineering
-description = Units of measure as required by the Climate and Forecast (CF) metadata conventions
-download_url = https://github.com/SciTools/cf-units
-keywords =
-    units
-    cf
-    netcdf
-    science
-    oceanography
-    meteorology
-    climate
-license = BSD
-license_files = LICENSE
-long_description = file: README.md
-long_description_content_type = text/markdown
-name = cf-units
-project_urls =
-    Code = https://github.com/SciTools/cf-units
-    Discussions = https://github.com/SciTools/cf-units/discussions
-    Issues = https://github.com/SciTools/cf-units/issues
-url = https://github.com/SciTools/cf-units
-version = attr: cf_units.__version__
-
-[options]
-include_package_data = True
-install_requires =
-    antlr4-python3-runtime ==4.11.1  # To update this, see cf_units/_udunits2_parser/README.md
-    cftime >=1.2
-    jinja2
-    numpy ==1.26.4
-    # udunits2 cannot be installed with pip, and it is expected to be
-    #  installed separately.
-packages = find_namespace:
-python_requires =
-    >=3.9
-zip_safe = False
-
-[options.extras_require]
-docs =
-    sphinx
-test =
-    codecov
-    cython
-    jinja2
-    pip
-    pytest
-    pytest-cov
-all =
-    pre-commit
-    %(docs)s
-    %(test)s
-
 [flake8]
 # References:
 #   https://flake8.readthedocs.io/en/latest/user/configuration.html
@@ -93,6 +30,3 @@ exclude =
     doc,
     etc,
     cf_units/_udunits2_parser/parser/*
-
-[aliases]
-test = pytest

setup.py

@@ -1,3 +1,8 @@
+"""Setup routines to enable cf-units' Cython elements.
+
+All other setup configuration is in `pyproject.toml`.
+"""
+
 import sys
 from distutils.sysconfig import get_config_var
 from os import environ
@@ -6,7 +11,8 @@
 
 from setuptools import Command, Extension, setup
 
-# Default to using cython, but use the .c files if it doesn't exist
+# Default to using cython, but use the .c files if it doesn't exist.
+#  Supports the widest possible range of developer setups.
 try:
     from Cython.Build import cythonize
 except ImportError:
@@ -40,27 +46,14 @@ def run(self):
                 path.unlink()
 
 
-def get_include_dirs():
-    include_dirs = []
-    include_dir = environ.get("UDUNITS2_INCDIR")
-    if include_dir is None:
-        include_dir = get_config_var("INCLUDEDIR")
-    if include_dir is not None:
-        include_dirs.append(include_dir)
-    return include_dirs
-
-
-def get_library_dirs():
-    library_dirs = []
-    library_dir = environ.get("UDUNITS2_LIBDIR")
-    if library_dir is None:
-        library_dir = get_config_var("LIBDIR")
-    if library_dir is not None:
-        library_dirs.append(library_dir)
-    return library_dirs
+def get_dirs(env_var: str, config_var: str):
+    """Get a directory from an environment variable or a distutils config variable."""
+    result = environ.get(env_var) or get_config_var(config_var)
+    return [result] if result else []
 
 
 def get_package_data():
+    """Find and correctly package the UDUNITS2 XML files for a wheel build."""
     package_data = {}
     # Determine whether we're building a wheel.
     if "bdist_wheel" in sys.argv:
@@ -99,6 +92,7 @@ def get_package_data():
 
 
 def numpy_build_ext(pars):
+    """Make the NumPy headers available for the Cython layer."""
     from setuptools.command.build_ext import build_ext as _build_ext
 
     class build_ext(_build_ext):
@@ -126,12 +120,16 @@ def _set_builtin(name, value):
         sys.argv.remove(FLAG_COVERAGE)
     print('enable: "linetrace" Cython compiler directive')
 
-library_dirs = get_library_dirs()
+include_dirs = get_dirs("UDUNITS2_INCDIR", "INCLUDEDIR")
+library_dirs = get_dirs("UDUNITS2_LIBDIR", "LIBDIR")
 
+# Some of the complexity MUST remain in setup.py due to its dynamic nature. To
+#  reduce confusion, the Extension is 100% defined here, rather than splitting
+#  between setup.py and pyproject.toml `ext-modules`.
 udunits_ext = Extension(
     f"{PACKAGE}._udunits2",
     [str(Path(f"{PACKAGE}") / f"_udunits2.{'pyx' if cythonize else 'c'}")],
-    include_dirs=get_include_dirs(),
+    include_dirs=include_dirs,
     library_dirs=library_dirs,
     libraries=["udunits2"],
     define_macros=DEFINE_MACROS,
@@ -141,6 +139,7 @@ def _set_builtin(name, value):
 )
 
 if cythonize:
+    # https://docs.cython.org/en/latest/src/userguide/source_files_and_compilation.html#distributing-cython-modules
     [udunits_ext] = cythonize(
         udunits_ext,
         compiler_directives=COMPILER_DIRECTIVES,