Python

• https://gto76.github.io/python-cheatsheet/

• Create a virtual env

pyenv virtualenv <python_version> <environment_name>

• Activate the versions

pyenv local <environment_name>

• Install a version with headers

#On MacOS
PYTHON_CONFIGURE_OPTS="--enable-framework" pyenv install VERSION
#On Linux
PYTHON_CONFIGURE_OPTS="--enable-shared" pyenv install 3.6.15

1. Raw text doesn't exist.
2. Use UTF8. Now. Everywhere.
3. In your code, precise file encoding and declare string as unicode.
4. Know you input encoding and decode with decode().
5. Encode your outputs as expected or in UTF-8 if you don't know the expected encoding with encode()

Here is how you can create a fully configured new project in a just a couple of minutes (assuming you have pyenv and poetry installed already).

poetry new my-project; cd my-project; ls
pyenv local 3.9.2
poetry env use python
poetry add --dev pytest-cov pre-commit flake8 mypy isort
poetry add --dev --allow-prereleases black
poetry shell

Add config to pyproject.toml:

[tool.isort]
multi_line_output = 3
include_trailing_comma = true
force_grid_wrap = 0
use_parentheses = true
line_length = 79

[tool.black]
line-length = 79
target-version = ['py38']
include = '\.pyi?$'
exclude = '''

(
  /(
      \.eggs         # exclude a few common directories in the
    | \.git          # root of the project
    | \.hg
    | \.mypy_cache
    | \.tox
    | \.venv
    | _build
    | buck-out
    | build
    | dist
  )/
  | foo.py           # also separately exclude a file named foo.py in
                     # the root of the project
)
'''

Create setup.cfg:

[flake8]
extend-ignore = E203

[mypy]
follow_imports = silent
strict_optional = True
warn_redundant_casts = True
warn_unused_ignores = True
disallow_any_generics = True
check_untyped_defs = True
no_implicit_reexport = True
disallow_untyped_defs = True
ignore_missing_imports = True

[mypy-tests.*]
ignore_errors = True

Create .pre-commit-config.yaml.

repos:
-   repo: https://github.com/pre-commit/pre-commit-hooks
    rev: v3.4.0
    hooks:
    -   id: trailing-whitespace
    -   id: end-of-file-fixer
    -   id: check-yaml
    -   id: check-added-large-files
-   repo: https://gitlab.com/pycqa/flake8
    rev: 3.8.4
    hooks:
    -   id: flake8
-   repo: https://github.com/psf/black
    rev: 20.8b1
    hooks:
      - id: black
-   repo: https://github.com/pre-commit/mirrors-mypy
    rev: v0.812
    hooks:
        - id: mypy
          additional_dependencies: [pydantic]  # add if use pydantic
-   repo: https://github.com/PyCQA/isort
    rev: 5.7.0
    hooks:
    -   id: isort

echo '.coverage' > .gitignore
echo '.vscode/\n.idea/' >> .gitignore
curl -s https://raw.githubusercontent.com/github/gitignore/master/Python.gitignore >> .gitignore
git init -b main
git add .
git commit -m 'Initial commit'
pre-commit install
pre-commit autoupdate
pre-commit run --all-files
pre-commit run --all-files