Fully automatic dependency injection for python
Project description
python-di
Fully automatic dependency injection for python 3.7, 3.8, 3.9, pypy3 using (not only) argument annotations / type hints.
Corresponds to clean architecture patterns and ideal for business applications created in DDD / Hexagonal architecture flavour. No external dependencies - uses only standard libraries.
Key features:
- automatic type matching based on type hints / type annotations - no manual configuration is needed, it just works out of the box
- configurable object aggregation injection -
DI can join
SomeClass
objects and inject into argument annotated asCollection[SomeClass]
- not harm existing codebase - no decorators, no extra metadata are needed in existing codebase to make app construction possible
- no singletons or global DI process state - app or any app components can be instantiated independently as many times as needed
- transparency of DI process - static dependency graph and injection plan is built, informative exceptions on error cases (like cyclic dependency or missing elements)
Help
Coming soon...
An Example
Application domain located in mod_simple.py
:
from typing import List
class Repo:
def read(self) -> List[str]:
raise NotImplementedError
class DomainAction:
def __init__(self, repo: Repo):
self.repo = repo
def present(self) -> str:
joined = ", ".join(self.repo.read())
return f"Data found: {joined}"
Application concretes located in mod_simple_impl.py
:
from typing import List
from mod_simple import Repo
class MockupRepo(Repo):
def read(self) -> List[str]:
return ["di", "test"]
Automatic application construction:
from di.declarative import DeclarativeApp, DeclarativeModule, scan_factories
import mod_simple, mod_simple_impl
def main():
# create app definition
app_def = DeclarativeApp(
DeclarativeModule(
# automatically add factories from `mod_simple` and `mod_simple_impl`
scan_factories(mod_simple, mod_simple_impl),
)
)
# build app
instance = app_def.build_instance()
# get initialized `DomainAction` object
action, = instance.values_by_type(mod_simple.DomainAction)
# check app works
assert action.present() == "Data found: di, test"
More examples
More working examples are available in tests/di/declarative/
.
Please see tests/di/declarative/test_build.py for reference.
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