Use .python-version

.github/CONTRIBUTING.md

@@ -33,29 +33,40 @@ Please report any harm to [Hynek Schlawack] in any way you find appropriate.
 
 You can (and should) run our test suite using [Nox].
 However, you’ll probably want a more traditional environment as well.
-We highly recommend to develop using the latest Python release because we try to take advantage of modern features whenever possible.
 
-First create a [virtual environment](https://virtualenv.pypa.io/) so you don't break your system-wide Python installation.
-It’s out of scope for this document to list all the ways to manage virtual environments in Python, but if you don’t already have a pet way, take some time to look at tools like [*direnv*](https://hynek.me/til/python-project-local-venvs/), [*virtualfish*](https://virtualfish.readthedocs.io/), and [*virtualenvwrapper*](https://virtualenvwrapper.readthedocs.io/).
+First, create a [virtual environment](https://virtualenv.pypa.io/) so you don't break your system-wide Python installation.
+We recommend using the Python version from the `.python-version` file in project's root directory.
 
-Next, get an up to date checkout of the *environ-config* repository:
+If you're using [*direnv*](https://direnv.net), you can automate the creation of a virtual environment with the correct Python version by adding the following `.envrc` to the project root after cloning it:
+
+```bash
+layout python python$(cat .python-version)
+```
+
+[Create a fork](https://github.com/hynek/environ-config/fork) of the *structlog* repository and clone it:
 
 ```console
-$ git clone git@github.com:hynek/environ-config.git
+$ git clone git@github.com:YOU/environ-config.git
 ```
 
-or if you prefer to use *Git* via `https`:
+Or if you prefer to use Git via HTTPS:
 
 ```console
-$ git clone https://github.com/hynek/environ-config.git
+$ git clone https://github.com/YOU/environ-config.git
 ```
 
-Change into the newly created directory and **after activating your virtual environment** install an editable version of *environ-config* along with its tests and docs requirements:
+> **Warning**
+> - **Before** you start working on a new pull request, use the "*Sync fork*" button in GitHub's web UI to ensure your fork is up to date.
+> - **Always create a new branch off `main` for each new pull request.**
+>   Yes, you can work on `main` in your fork and submit pull requests.
+>   But this will *inevitably* lead to you not being able to synchronize your fork with upstream and having to start over.
+
+Change into the newly created directory and after activating a virtual environment, install an editable version of *environ-config* along with its tests and docs requirements:
 
 ```console
 $ cd environ-config
-$ pip install --upgrade pip wheel setuptools  # PLEASE don't skip this step
-$ pip install -e '.[dev]'
+$ python -Im pip install --upgrade pip wheel  # PLEASE don't skip this step
+$ python -Im pip install -e '.[dev]'
 ```
 
 At this point,

.github/workflows/ci.yml

@@ -12,13 +12,16 @@ env:
   FORCE_COLOR: "1" # Make tools pretty.
   PIP_DISABLE_PIP_VERSION_CHECK: "1"
   PIP_NO_PYTHON_VERSION_WARNING: "1"
-  PYTHON_LATEST: "3.11"
   SETUPTOOLS_SCM_PRETEND_VERSION: "1.0" # avoid warnings about shallow checkout
 
   # For re-actors/checkout-python-sdist
   sdist-artifact: python-package-distributions
   sdist-name: environ_config-1.0.tar.gz
 
+  # N.B. default Python version for setup-python comes from the .python-version
+  # file at the root of the project.
+
+
 permissions:
   contents: read
 
@@ -30,8 +33,6 @@ jobs:
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-python@v4
-        with:
-          python-version: ${{ env.PYTHON_LATEST }}
       - run: python -Im pip install build
 
       - run: python -Im build --sdist
@@ -105,9 +106,6 @@ jobs:
           source-tarball-name: ${{ env.sdist-name }}
           workflow-artifact-name: ${{ env.sdist-artifact }}
       - uses: actions/setup-python@v4
-        with:
-          # Use latest Python, so it understands all syntax.
-          python-version: ${{ env.PYTHON_LATEST }}
 
       - run: python -Im pip install --upgrade coverage[toml]
 
@@ -188,8 +186,6 @@ jobs:
     steps:
       - uses: actions/checkout@v3
       - uses: actions/setup-python@v4
-        with:
-          python-version: ${{ env.PYTHON_LATEST }}
 
       - run: python -Im pip install -e .[dev]
       - run: python -c 'import environ; print(environ.__version__)'

.python-version

@@ -0,0 +1 @@
+3.11