: If a directory doesn't have the file, the tool searches "up" the folder tree until it finds one or falls back to a global default. Setting Up Your Environment
: Defines the required Python version range in the pyproject.toml file under the [tool.poetry.dependencies] section. .python version
In modern development, different projects often require different Python versions. For example, an older legacy app might need , while a new data science project requires Python 3.12 . Managing these manually by changing global paths is error-prone. Tools like pyenv solve this by looking for a .python-version file. How the .python-version File Works : If a directory doesn't have the file,
: Match the version in this file to the version used in your production environment (e.g., your Dockerfile or AWS Lambda runtime) to ensure consistent behavior across all stages of development. Common Alternatives For example, an older legacy app might need
: Use a command like pyenv install 3.12.0 .
: Navigate to your project folder and run pyenv local 3.12.0 . This automatically generates the .python-version file for you. Best Practices for Teams