A simple Python dependency injection framework.
This project is under active development. The following example does not represent the final state for the project.
You can install this project from pypi.
pip install python-injection-framework
The injection framework is configured to inject any default values for method arguments that are instances
of providers.Provider
.
This implementation works by wrapping decorators around methods any patching any unfilled providers.Provider
default
arguments at runtime.
All dependency injection is lazily evaluated so providers are only evaluated when a method is called. This approach is optimal as it reduces necessary computation for expensive services and reduces
With this approach you can automatically inject functions at load time using the @wiring.inject
decorator.
from pif import wiring, providers
@wiring.inject # <- automatically injects providers.Provider default arguments!
def my_function(a: str = providers.ExistingSingleton("hello world")):
return a
if __name__ == "__main__":
assert "hello world" == my_function()
With this approach you can wire all methods in the specified modules.
from pif import wiring, providers
def my_function(a: str = providers.ExistingSingleton("hello world")):
return a
if __name__ == "__main__":
wiring.wire([__name__]) # <- dynamically inject methods with providers.Provider default arguments!
assert "hello world" == my_function()
This package provides a simple mechanism to override providers. This can be very useful when it comes to mocking services for testing or dynamically patching application behavior based on application configuration.
If you want to patch a value all you need to do is call .override()
on the provider in question. If you are wanting to
override an existing singleton you may call the convenience method .override_existing()
.
from pif import wiring, providers
StringProvider = providers.ExistingSingleton("hello world")
@wiring.inject
def my_function(a: str = StringProvider):
return a
if __name__ == "__main__":
assert "hello world" == my_function()
override = StringProvider.override_existing("overridden_1")
assert "overridden_1"
If you want more control around the override lifecycles then you may use the Override
context manager.
from pif import wiring, providers
StringProvider = providers.ExistingSingleton("hello world")
@wiring.inject
def my_function(a: str = StringProvider):
return a
if __name__ == "__main__":
assert "hello world" == my_function()
OverrideProvider = providers.ExistingSingleton("overridden_1")
with StringProvider.override(OverrideProvider):
assert "overridden_1" == my_function()
with OverrideProvider.override_existing("overridden_2"):
assert "overridden_2" == my_function() # You can even stack overrides!!
assert "overridden_1" == my_function()
assert "hello world" == my_function()
If you would like to see more examples, feel free to check out examples/.
-
Clone the repository and configure Poetry 🪄
git clone [email protected]:scottzach1/Python-Injection-Framework.git cd Python-Injection-Framework poetry install
-
Configure pre-commit hooks 🪝
pre-commit install
-
Write your changes! 💻️
-
Run test cases 🧪
pytest tests/
-
Submit a Pull Request
↖️
Zac Scott (scottzach1) |