python-dependency-injector/docs/providers/callable.rst

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Callable providers
------------------
``Callable`` provider is a provider that decorates particular callable with
some injections. Every call of this provider returns result of call of initial
callable.
``Callable`` provider uses ``KwArg`` injections. ``KwArg`` injections are
done by passing injectable values like keyword arguments during call time.
Context keyword arguments have higher priority than ``KwArg`` injections.
Example:
.. code-block:: python
"""`Callable` providers examples."""
from objects.providers import Callable
from objects.providers import Singleton
from objects.injections import KwArg
class UserService(object):
"""Example class UserService."""
def get_by_id(self, id):
"""Return user info by user id."""
return {'id': id, 'login': 'example_user'}
def get_user_by_id(user_id, users_service):
"""Example function that has input arg and dependency on database."""
return users_service.get_by_id(user_id)
# UserService and get_user_by_id providers:
users_service = Singleton(UserService)
get_user_by_id = Callable(get_user_by_id,
KwArg('users_service', users_service))
# Making some asserts:
assert get_user_by_id(1) == {'id': 1, 'login': 'example_user'}
assert get_user_by_id(2) == {'id': 2, 'login': 'example_user'}
# Context keyword arguments priority example:
class UserServiceMock(object):
"""Example class UserService."""
def get_by_id(self, id):
"""Return user info by user id."""
return {'id': id, 'login': 'mock'}
user_service_mock = UserServiceMock()
user3 = get_user_by_id(1, users_service=user_service_mock)
assert user3 == {'id': 1, 'login': 'mock'}