Mucking around with `distutils` command packages

dumpmeta.py

#!/usr/bin/env python3

from distutils.cmd import Command
import json


def to_json(v):
    if (v is None) or isinstance(v, (bool, int, str)):
        return v
    elif isinstance(v, list):
        return [to_json(e) for e in v]
    elif isinstance(v, dict):
        return dict([
            (to_json(k), to_json(e))
            for k, e
            in v.items()
        ])
    else:
        return repr(v)


class dumpmeta(Command):
    """
    Dump the metadata for a `setup.py` script in JSON.
    """
    user_options = []

    def initialize_options(self):
        pass

    def finalize_options(self):
        pass

    def run(self):
        metadata = {}
        for attr in dir(self.distribution):
            if attr.startswith("_"):
                continue

            value = getattr(self.distribution, attr)
            if hasattr(value, "__call__"):
                if not attr.startswith("get_"):
                    continue
                try:
                    value = value()
                    attr = attr[4:]  # strip get_ prefix
                except:
                    continue
            metadata[attr] = to_json(value)

        print (json.dumps(metadata, indent=4))

output.txt

RC=0 stuartl@rikishi ~/projects/wicen/rfid/aioax25 $ python3 setup.py --command-package=dumpsetup dumpmeta
running dumpmeta
{
    "author": "Stuart Longland VK4MSL",
    "author_email": "me@vk4msl.id.au",
    "cffi_modules": null,
    "classifiers": [
        "Development Status :: 2 - Pre-Alpha",
        "Environment :: No Input/Output (Daemon)",
        "Framework :: AsyncIO",
        "Intended Audience :: Developers",
        "License :: OSI Approved :: GNU General Public License v2 or later (GPLv2+)",
        "Operating System :: POSIX",
        "Programming Language :: Python :: 3 :: Only",
        "Topic :: Communications :: Ham Radio"
    ],
    "cmdclass": {
        "dumpmeta": "<class 'dumpsetup.dumpmeta.dumpmeta'>"
    },
    "command_obj": {
        "dumpmeta": "<dumpsetup.dumpmeta.dumpmeta object at 0x7f5951c3e310>"
    },
    "command_options": {
        "tool:pytest": {
            "log_cli": "('setup.cfg', 'true')"
        },
        "aliases": {},
        "dumpmeta": {}
    },
    "command_packages": [
        "distutils.command",
        "dumpsetup"
    ],
    "commands": [
        "dumpmeta"
    ],
    "common_usage": "Common commands: (see '--help-commands' for more)\n\n  setup.py build      will build the package underneath 'build/'\n  setup.py install    will install the package\n",
    "contact": "Stuart Longland VK4MSL",
    "contact_email": "me@vk4msl.id.au",
    "data_files": null,
    "dependency_links": [],
    "description": "Asynchronous AX.25 interface in pure Python using asyncio",
    "display_option_names": [
        "help_commands",
        "name",
        "version",
        "fullname",
        "author",
        "author_email",
        "maintainer",
        "maintainer_email",
        "contact",
        "contact_email",
        "url",
        "license",
        "licence",
        "description",
        "long_description",
        "platforms",
        "classifiers",
        "keywords",
        "provides",
        "requires",
        "obsoletes"
    ],
    "display_options": [
        "('help-commands', None, 'list all available commands')",
        "('name', None, 'print package name')",
        "('version', 'V', 'print package version')",
        "('fullname', None, 'print <package name>-<version>')",
        "('author', None, \"print the author's name\")",
        "('author-email', None, \"print the author's email address\")",
        "('maintainer', None, \"print the maintainer's name\")",
        "('maintainer-email', None, \"print the maintainer's email address\")",
        "('contact', None, \"print the maintainer's name if known, else the author's\")",
        "('contact-email', None, \"print the maintainer's email address if known, else the author's\")",
        "('url', None, 'print the URL for this package')",
        "('license', None, 'print the license of the package')",
        "('licence', None, 'alias for --license')",
        "('description', None, 'print the package description')",
        "('long-description', None, 'print the long package description')",
        "('platforms', None, 'print the list of platforms')",
        "('classifiers', None, 'print the list of classifiers')",
        "('keywords', None, 'print the list of keywords')",
        "('provides', None, 'print the list of packages/modules provided')",
        "('requires', None, 'print the list of packages/modules required')",
        "('obsoletes', None, 'print the list of packages/modules made obsolete')"
    ],
    "dist_files": [],
    "dry_run": 0,
    "eager_resources": null,
    "entry_points": null,
    "exclude_package_data": null,
    "ext_modules": null,
    "ext_package": null,
    "extra_path": null,
    "extras_require": {},
    "fullname": "aioax25-0.0.12",
    "cmdline_options": {},
    "command_list": [
        "('build', 'build everything needed to install')",
        "('build_py', '\"build\" pure Python modules (copy to build directory)')",
        "('build_ext', 'build C/C++ and Cython extensions (compile/link to build directory)')",
        "('build_clib', 'build C/C++ libraries used by Python extensions')",
        "('build_scripts', '\"build\" scripts (copy and fixup #! line)')",
        "('clean', \"clean up temporary files from 'build' command\")",
        "('install', 'install everything from build directory')",
        "('install_lib', 'install all Python modules (extensions and pure Python)')",
        "('install_headers', 'install C/C++ header files')",
        "('install_scripts', 'install scripts (Python or otherwise)')",
        "('install_data', 'install data files')",
        "('sdist', 'create a source distribution (tarball, zip file, etc.)')",
        "('register', 'register the distribution with the Python package index')",
        "('bdist', 'create a built (binary) distribution')",
        "('bdist_dumb', 'create a \"dumb\" built distribution')",
        "('bdist_rpm', 'create an RPM distribution')",
        "('check', 'perform some checks on the package')",
        "('upload', 'upload binary package to PyPI')",
        "('dumpmeta', '(no description available)')",
        "('compile_catalog', 'compile message catalogs to binary MO files')",
        "('extract_messages', 'extract localizable strings from the project code')",
        "('init_catalog', 'create a new catalog based on a POT file')",
        "('update_catalog', 'update message catalogs from a POT file')",
        "('isort', 'Run isort on modules registered in setuptools')",
        "('nosetests', 'Run unit tests using nosetests')",
        "('alias', 'define a shortcut to invoke one or more commands')",
        "('bdist_egg', 'create an \"egg\" distribution')",
        "('develop', \"install package in 'development mode'\")",
        "('dist_info', 'DO NOT CALL DIRECTLY, INTERNAL ONLY: create .dist-info directory')",
        "('easy_install', 'Find/get/install Python packages')",
        "('editable_wheel', 'DO NOT CALL DIRECTLY, INTERNAL ONLY: create PEP 660 editable wheel')",
        "('egg_info', \"create a distribution's .egg-info directory\")",
        "('install_egg_info', 'Install an .egg-info directory for the package')",
        "('rotate', 'delete older distributions, keeping N newest files')",
        "('saveopts', 'save supplied options to setup.cfg or other config file')",
        "('setopt', 'set an option in setup.cfg or another config file')",
        "('test', 'run unit tests after in-place build (deprecated)')",
        "('upload_docs', 'Upload documentation to sites other than PyPi such as devpi')",
        "('build_rust', 'build Rust extensions (compile/link to build directory)')",
        "('clean_rust', 'clean Rust extensions (compile/link to build directory)')",
        "('build_sphinx', 'Build Sphinx documentation')",
        "('bdist_wheel', 'create a wheel distribution')"
    ],
    "download_url": null,
    "egg_cache_dir": "./.eggs",
    "keywords": 0,
    "license": 0,
    "long_description": 0,
    "maintainer": 0,
    "maintainer_email": 0,
    "name": 0,
    "obsoletes": 0,
    "platforms": 0,
    "provides": 0,
    "requires": 0,
    "url": 0,
    "version": 0,
    "global_options": [
        "('verbose', 'v', 'run verbosely (default)', 1)",
        "('quiet', 'q', 'run quietly (turns verbosity off)')",
        "('dry-run', 'n', \"don't actually do anything\")",
        "('help', 'h', 'show detailed help message')",
        "('no-user-cfg', None, 'ignore pydistutils.cfg in your home directory')"
    ],
    "have_run": {
        "dumpmeta": 0
    },
    "headers": null,
    "help": 0,
    "help_commands": 0,
    "include_dirs": null,
    "include_package_data": null,
    "install_requires": [
        "pyserial",
        "signalslot",
        "pyserial_asyncio"
    ],
    "libraries": null,
    "licence": 0,
    "message_extractors": null,
    "metadata": "<distutils.dist.DistributionMetadata object at 0x7f59521508d0>",
    "namespace_packages": null,
    "negative_opt": {
        "quiet": "verbose"
    },
    "package_data": {},
    "package_dir": {},
    "packages": [
        "aioax25",
        "aioax25.aprs"
    ],
    "password": "",
    "pbr": null,
    "py_modules": null,
    "python_requires": null,
    "rust_extensions": null,
    "script_args": [
        "--command-package=dumpsetup",
        "dumpmeta"
    ],
    "script_name": "setup.py",
    "scripts": null,
    "setup_requires": [],
    "src_root": null,
    "test_loader": null,
    "test_runner": null,
    "test_suite": null,
    "tests_require": null,
    "use_2to3": null,
    "use_calver": null,
    "use_incremental": null,
    "use_scm_version": null,
    "verbose": 1,
    "want_user_cfg": true,
    "zip_safe": null
}

references.txt

https://docs.python.org/3/distutils/apiref.html#module-distutils.command.build
https://docs.python.org/3/distutils/apiref.html#creating-a-new-distutils-command

The referenced 'template' is very sparse:
https://github.com/pypa/distutils/blob/main/distutils/command/command_template