First working commit

.gitignore

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+# Byte-compiled / optimized / DLL files
+__pycache__/
+*.py[cod]
+*$py.class
+
+# C extensions
+*.so
+
+# Distribution / packaging
+.Python
+build/
+develop-eggs/
+dist/
+downloads/
+eggs/
+.eggs/
+lib/
+lib64/
+parts/
+sdist/
+var/
+wheels/
+*.egg-info/
+.installed.cfg
+*.egg
+MANIFEST
+
+# PyInstaller
+#  Usually these files are written by a python script from a template
+#  before PyInstaller builds the exe, so as to inject date/other infos into it.
+*.manifest
+*.spec
+
+# Installer logs
+pip-log.txt
+pip-delete-this-directory.txt
+
+# Unit test / coverage reports
+htmlcov/
+.tox/
+.coverage
+.coverage.*
+.cache
+nosetests.xml
+coverage.xml
+*.cover
+.hypothesis/
+.pytest_cache/
+
+# Translations
+*.mo
+*.pot
+
+# Django stuff:
+*.log
+local_settings.py
+db.sqlite3
+
+# Flask stuff:
+instance/
+.webassets-cache
+
+# Scrapy stuff:
+.scrapy
+
+# Sphinx documentation
+docs/_build/
+
+# PyBuilder
+target/
+
+# Jupyter Notebook
+.ipynb_checkpoints
+
+# pyenv
+.python-version
+
+# celery beat schedule file
+celerybeat-schedule
+
+# SageMath parsed files
+*.sage.py
+
+# Environments
+.env
+.venv
+env/
+venv/
+ENV/
+env.bak/
+venv.bak/
+
+# Spyder project settings
+.spyderproject
+.spyproject
+
+# Rope project settings
+.ropeproject
+
+# mkdocs documentation
+/site
+
+# mypy
+.mypy_cache/
+
+# VS Code
+.vscode
+
+
+.node_modules
+node_modules

README.rst

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+==============
+single-version
+==============
+
+.. image:: https://madewithlove.now.sh/vn?heart=true&colorA=%23ffcd00&colorB=%23da251d
+.. image:: https://badgen.net/pypi/v/single-version
+
+Utility to let you have a single source of version in your code base.
+
+This utility targets modern Python projects which have layout generated by `Poetry`_, with a *pyproject.toml* file in place of *setup.py*. With this layout, the project initially has two places to maintain version string: one in *pyproject.toml* file and one in some *\*.py* file (normally *__init__.py*):
+
+.. code-block:: toml
+
+    # pyproject.toml
+    [tool.poetry]
+    name = "your-package"
+    version = "0.1.0"
+
+.. code-block:: python
+
+    # your_package/__init__.py
+    __version__ = "0.1.0"
+
+This duplicity often leads to inconsistency when you, the author, forget to update both.
+
+*single-version* is born to solve that headache circumstance. By convention, it chooses the *pyproject.toml* file as original source of version string. Your project's ``__version__`` variable then is computed from it. When your package is already deployed and installed to some system, the version string will be retrieved from that Python environment (the *pyproject.toml* is not included in distribution file).
+
+Years ago, to retrieve version for an installed package, ones often used `pkg_resources`_, which has well-known issue of causing slow import. Learning from that mistake, *single-version* use |importlib.metadata|_, which becomes standard from Python 3.8, instead.
+
+
+Usage
+-----
+
+Add ``single_version`` as your project dependency:
+
+.. code-block:: sh
+
+    poetry add single-version
+
+
+Assume that you define ``__version__`` variable in `your_package/__init__.py` file:
+
+.. code-block:: python
+
+    from pathlib import Path
+
+    from single_version import get_version
+
+
+    __version__ = get_version('your_package', Path(__file__).parent.parent)
+
+
+.. _Poetry: https://python-poetry.org/
+.. _pkg_resources: https://setuptools.readthedocs.io/en/latest/pkg_resources.html
+.. |importlib.metadata| replace:: ``importlib.metadata``
+.. _importlib.metadata: https://docs.python.org/3.8/library/importlib.metadata.html