extras

Package that allows to make assertions about extras being installed or not.

For the detailed explanation read this blog post.

Usage

For the pyproject.toml users

[tool.poetry.dependencies]
package-extras = { version = "^0.2.0", optional = true }
# your actual extras below
psycopg2 = { version = "^2.9", optional = true }
mysqlclient = { version = "^1.3", optional = true }

[tool.poetry.extras]
databases = ["package-extras", "mysqlclient", "psycopg2"]

setup.py equivalent

extras_require = \
{'databases': ['package-extras>=0.2.0',
               'psycopg2>=2.9,<3.0',
               'mysqlclient>=1.3,<2.0']}

setup_kwargs = {
    # ... rest of the arguments
    'extras_require': extras_require,
}
setup(**setup_kwargs)

Add this or similar block to your code (likely top-level __init__.py file)

import warnings

try:
    import package_extras
except ModuleNotFoundError:
    pass
else:
    warnings.warn(
        "'test_package[databases]' extra is deprecated "
        "and will be removed in a future release.",
        category=DeprecationWarning,
        stacklevel=2,
    )

Or in case you want to assert the opposite (make sure that extras have been installed)

import warnings

try:
    import package_extras
except ModuleNotFoundError:
    warnings.warn(
        "You are going to use functionality that depends on 'databases' extras. "
        "Please install 'test_package[databases]' to proceed.",
        category=ImportWarning,
        stacklevel=2,
    )

NOTE: ImportWarning is ignored by default, so you either need to run python -W all or use RuntimeWarning instead.

After installation via pip install test_package[databases] your package users will get this warning.

>>> import test_package
DeprecationWarning: 'test_package[databases]' extra is deprecated and will be removed in a future release.

Development

$ poetry install
$ poetry build

$ poetry config pypi-token.pypi my-token
$ poetry publish