Convert setup.py metadata to setup.cfg (#457)

Use [setup-py-upgrade](https://pypi.org/project/setup-py-upgrade/) plus some manual editing to move to the declarative metadata format.

HISTORY.rst

@@ -6,6 +6,12 @@ Pending
 
 .. Insert new release notes below this line
 
+* Converted setuptools metadata to configuration file. This meant removing the
+  ``__version__`` attribute from the package. If you want to inspect the
+  installed version, use
+  ``pkg_resources.get_distribution("django-cors-headers").version``
+  (`docs <https://setuptools.readthedocs.io/en/latest/pkg_resources.html#getting-or-creating-distributions>`__).
+
 3.1.1 (2019-09-30)
 ------------------
 

corsheaders/__init__.py

@@ -1,3 +1 @@
 from corsheaders.checks import check_settings  # noqa: F401
-
-__version__ = "3.1.1"

setup.cfg

@@ -1,3 +1,48 @@
+[metadata]
+name = django-cors-headers
+version = 3.1.1
+description = django-cors-headers is a Django application for handling the server headers required for Cross-Origin Resource Sharing (CORS).
+long_description = file: README.rst, HISTORY.rst
+long_description_content_type = text/x-rst
+author = Otto Yiu
+author_email = otto@live.ca
+maintainer = Adam Johnson
+maintainer_email = me@adamj.eu
+url = https://github.com/adamchainz/django-cors-headers
+project_urls =
+    Changelog = https://github.com/adamchainz/django-cors-headers/blob/master/HISTORY.rst
+license = MIT License
+keywords =
+    django
+    cors
+    middleware
+    rest
+    api
+classifiers =
+    Development Status :: 5 - Production/Stable
+    Environment :: Web Environment
+    Framework :: Django
+    Framework :: Django :: 1.11
+    Framework :: Django :: 2.0
+    Framework :: Django :: 2.1
+    Framework :: Django :: 2.2
+    Intended Audience :: Developers
+    License :: OSI Approved :: MIT License
+    Operating System :: OS Independent
+    Programming Language :: Python
+    Programming Language :: Python :: 3
+    Programming Language :: Python :: 3.5
+    Programming Language :: Python :: 3.6
+    Programming Language :: Python :: 3.7
+    Topic :: Software Development :: Libraries :: Application Frameworks
+    Topic :: Software Development :: Libraries :: Python Modules
+license_file = LICENSE
+
+[options]
+packages = corsheaders
+install_requires = Django>=1.11
+python_requires = >=3.5
+
 [flake8]
 max-line-length = 80
 select = C,E,F,W,B,B950
@@ -12,11 +57,8 @@ line_length = 88
 multi_line_output = 3
 use_parentheses = True
 
-[metadata]
-license_file = LICENSE
-
 [tool:multilint]
 paths = corsheaders
-        runtests.py
-        tests
-        setup.py
+    runtests.py
+    tests
+    setup.py

setup.py

@@ -1,64 +1,3 @@
-import os
-import re
-
 from setuptools import setup
 
-
-def get_version(filename):
-    with open(filename, "r") as fp:
-        contents = fp.read()
-    return re.search(r"__version__ = ['\"]([^'\"]+)['\"]", contents).group(1)
-
-
-version = get_version(os.path.join("corsheaders", "__init__.py"))
-
-with open("README.rst", "r") as readme_file:
-    readme = readme_file.read()
-
-with open("HISTORY.rst", "r") as history_file:
-    history = history_file.read()
-
-setup(
-    name="django-cors-headers",
-    version=version,
-    description=(
-        "django-cors-headers is a Django application for handling the server "
-        "headers required for Cross-Origin Resource Sharing (CORS)."
-    ),
-    long_description=readme + "\n\n" + history,
-    author="Otto Yiu",
-    author_email="otto@live.ca",
-    maintainer="Adam Johnson",
-    maintainer_email="me@adamj.eu",
-    url="https://github.com/adamchainz/django-cors-headers",
-    project_urls={
-        "Changelog": (
-            "https://github.com/adamchainz/django-cors-headers"
-            + "/blob/master/HISTORY.rst"
-        )
-    },
-    packages=["corsheaders"],
-    license="MIT License",
-    keywords=["django", "cors", "middleware", "rest", "api"],
-    install_requires=["Django>=1.11"],
-    python_requires=">=3.5",
-    classifiers=[
-        "Development Status :: 5 - Production/Stable",
-        "Environment :: Web Environment",
-        "Framework :: Django",
-        "Framework :: Django :: 1.11",
-        "Framework :: Django :: 2.0",
-        "Framework :: Django :: 2.1",
-        "Framework :: Django :: 2.2",
-        "Intended Audience :: Developers",
-        "License :: OSI Approved :: MIT License",
-        "Operating System :: OS Independent",
-        "Programming Language :: Python",
-        "Programming Language :: Python :: 3",
-        "Programming Language :: Python :: 3.5",
-        "Programming Language :: Python :: 3.6",
-        "Programming Language :: Python :: 3.7",
-        "Topic :: Software Development :: Libraries :: Application Frameworks",
-        "Topic :: Software Development :: Libraries :: Python Modules",
-    ],
-)
+setup()