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https://github.com/adriangb/di
Pythonic dependency injection
https://github.com/adriangb/di
dependency-injector python
Last synced: 2 days ago
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Pythonic dependency injection
- Host: GitHub
- URL: https://github.com/adriangb/di
- Owner: adriangb
- License: mit
- Created: 2021-07-26T06:11:37.000Z (about 3 years ago)
- Default Branch: main
- Last Pushed: 2023-10-09T21:46:21.000Z (12 months ago)
- Last Synced: 2024-04-14T07:15:06.191Z (6 months ago)
- Topics: dependency-injector, python
- Language: Python
- Homepage: https://www.adriangb.com/di/
- Size: 6.37 MB
- Stars: 273
- Watchers: 4
- Forks: 12
- Open Issues: 12
-
Metadata Files:
- Readme: README.md
- Contributing: docs/contributing.md
- License: LICENSE.txt
- Code of conduct: CODE_OF_CONDUCT.md
Awesome Lists containing this project
README
# `di`: dependency injection toolkit
`di` is a modern dependency injection toolkit, modeled around the simplicity of FastAPI's dependency injection.
Key features:
- **Intuitive**: simple API, inspired by [FastAPI].
- **Auto-wiring**: `di` supports auto-wiring using type annotations.
- **Scopes**: inspired by [pytest scopes], but defined by users (no fixed "request" or "session" scopes).
- **Composable**: decoupled internal APIs give you the flexibility to customize wiring, execution and binding.
- **Performant**: `di` can execute dependencies in parallel and cache results ins scopes. Performance critical parts are written in [🦀] via [graphlib2].
## Installation
```shell
pip install di[anyio]
```
⚠️ This project is a work in progress. Until there is 1.X.Y release, expect breaking changes. ⚠️
## Simple Example
Here is a simple example of how `di` works:
```python
from dataclasses import dataclass
from di import Container
from di.dependent import Dependent
from di.executors import SyncExecutor
class A:
...
class B:
...
@dataclass
class C:
a: A
b: B
def main():
container = Container()
executor = SyncExecutor()
solved = container.solve(Dependent(C, scope="request"), scopes=["request"])
with container.enter_scope("request") as state:
c = solved.execute_sync(executor=executor, state=state)
assert isinstance(c, C)
assert isinstance(c.a, A)
assert isinstance(c.b, B)
```
For more examples, see our [docs].
### Why do I need dependency injection in Python? Isn't that a Java thing?
Dependency injection is a software architecture technique that helps us achieve [inversion of control] and [dependency inversion] (one of the five [SOLID] design principles).
It is a common misconception that traditional software design principles do not apply to Python.
As a matter of fact, you are probably using a lot of these techniques already!
For example, the `transport` argument to httpx's Client ([docs](https://www.python-httpx.org/advanced/#custom-transports)) is an excellent example of dependency injection. Pytest, arguably the most popular Python test framework, uses dependency injection in the form of [pytest fixtures].
Most web frameworks employ inversion of control: when you define a view / controller, the web framework calls you! The same thing applies to CLIs (like [click]) or TUIs (like [Textual]). This is especially true for many newer web frameworks that not only use inversion of control but also dependency injection. Two great examples of this are [FastAPI] and [BlackSheep].
For a more comprehensive overview of Python projects related to dependency injection, see [Awesome Dependency Injection in Python].
## Project Aims
This project aims to be a dependency injection toolkit, with a focus on providing the underlying dependency injection functionality for other libraries.
In other words, while you could use this as a standalone dependency injection framework, you may find it to be a bit terse and verbose. There are also much more mature standalone dependency injection frameworks; I would recommend at least looking into [python-dependency-injector] since it is currently the most popular / widely used of the bunch.
For more background, see our [docs].
[🦀]: https://www.rust-lang.org
[graphlib2]: https://github.com/adriangb/graphlib2
[docs]: https://www.adriangb.com/di/
[binds]: binds.md
[dependency inversion]: https://en.wikipedia.org/wiki/Dependency_inversion_principle
[SOLID]: https://en.wikipedia.org/wiki/SOLID
[inversion of control]: https://en.wikipedia.org/wiki/Inversion_of_control
[click]: https://click.palletsprojects.com/en/8.0.x/
[Textual]: https://github.com/willmcgugan/textual
[FastAPI]: https://fastapi.tiangolo.com/tutorial/dependencies/
[BlackSheep]: https://www.neoteroi.dev/blacksheep/dependency-injection/
[Awesome Dependency Injection in Python]: https://github.com/sfermigier/awesome-dependency-injection-in-python
[python-dependency-injector]: https://github.com/ets-labs/python-dependency-injector
[pytest scopes]: https://docs.pytest.org/en/6.2.x/fixture.html#scope-sharing-fixtures-across-classes-modules-packages-or-session
[pytest fixtures]: https://docs.pytest.org/en/6.2.x/fixture.html