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Python How to setup python projects

Links: 108 Python Index

Using Pyenv

  • It is used for managing multiple python versions.

Installation

  • brew install pyenv - installing pyenv
  • Add the following to your ~/.zshrc file
    • eval "$(pyenv init -)"

Commands

  • pyenv versions - List all the python versions that are available for pyenv
  • List all the python versions that can be installed
    • pyenv install -l
    • pyenv install -l | grep 3.9
  • pyenv install 3.9.7 - Install a specific version of python
  • pyenv global 3.10.4 - use a python version for all the terminals
    • Now whenever you invoke python, pip etc., an executable from the Pyenv-provided 3.10.4 installation will be run instead of the system Python.
  • pyenv shell <version> - select just for current shell session
  • pyenv local <version> - automatically select whenever you are in the current directory (or its subdirectories)
    • Creates a .python-version file
  • Using system as a version name would reset the selection to your system-provided Python.
  • Uninstalling python versions:
    • As time goes on, you will accumulate Python versions in your $(pyenv root)/versions directory.
    • To remove old Python versions, use pyenv uninstall <versions>.
    • Alternatively, you can simply rm -rf the directory of the version you want to remove.
      • You can find the directory of a particular Python version with the pyenv prefix command, e.g. pyenv prefix 2.6.8.
So first you will set the python version that you want to use using pyenv and then use python -m venv <virtual-env-name> to create a virtual environment.
  • pyenv doesn't create virtual envs, just installs python versions.
  • After selecting a specific version of pyenv create a virtual env using venv.

Using poetry

  • brew install poetry - installing poetry
  • All the important metadata is in pyproject.toml
  • Poetry also maintains a lock file for dependency management.

Commands

  • poetry new <project-name> - Creating a new project:
  • Instead of creating a new project, Poetry can be used to initialise a pre-populated directory. To interactively create a pyproject.toml file in directory pre-existing-project:
    • cd pre-existing-project; poetry init
  • poetry run pytest - Running tests
    • Uses the pytest that comes with poetry.
  • poetry install - Install all the dependencies on cloning the project:
  • poetry shell - Spawn a new shell and activate the virtual env:
  • poetry env use /full/path/to/python - We can tell poetry which environment to use.
    • We can do this after creating the virtual environment using venv.
  • poetry env info - List the virtualenv and system python versions and locations.
  • Show installed packages and their dependencies:
    • poetry show
    • poetry show --tree

Installing Dependencies

  • Add them to pyproject.toml under tool.poetry.dependencies
  • Easier is to use the add switch though:
    • poetry add <dependency-name>
    • poetry add pendulum@^2.0.5: for a specific version
    • from git: poetry add git+https://github.com/sdispater/pendulum.git
    • Remove a dependency: poetry remove <dependency-name>
  • For dev dependencies:
    • poetry add --dev pytest
    • poetry add -D pytest

Using Scripts

[tool.poetry.scripts]
my-script = "src.main:main"
- poetry run my-script - Running the main function of the main.py inside src.

Sample folder structure

attachments/Pasted image 20220916234253.jpg

If you want to use absolute imports properly without hassle run the following command at the root of the project (inside the python-project folder)

export PYTHONPATH="$(pwd)"

Last updated: 2023-01-16