What is this Python project?

Dependency Injector is a dependency injection framework for Python.

It helps implementing the dependency injection principle.

Key features of the Dependency Injector:

• Providers. Provides Factory, Singleton, Callable, Coroutine, Object, List, Dict, Configuration, Resource, Dependency and Selector providers that help assembling your objects. See Providers.
• Overriding. Can override any provider by another provider on the fly. This helps in testing and configuring dev / stage environment to replace API clients with stubs etc. See Provider overriding.
• Configuration. Reads configuration from yaml & ini files, environment variables and dictionaries. See Configuration provider.
• Containers. Provides declarative and dynamic containers. See Containers.
• Resources. Helps with initialization and configuring of logging, event loop, thread or process pool, etc. Can be used for per-function execution scope in tandem with wiring. See Resource provider.
• Wiring. Injects dependencies into functions and methods. Helps integrating with other frameworks: Django, Flask, Aiohttp, Sanic, FastAPI, etc. See Wiring.
• Typing. Provides typing stubs, mypy-friendly. See Typing and mypy.
• Performance. Fast. Written in Cython.
• Maturity. Mature and production-ready. Well-tested, documented and supported.

from dependency_injector import containers, providers
from dependency_injector.wiring import inject, Provide


class Container(containers.DeclarativeContainer):

    config = providers.Configuration()

    api_client = providers.Singleton(
        ApiClient,
        api_key=config.api_key,
        timeout=config.timeout.as_int(),
    )

    service = providers.Factory(
        Service,
        api_client=api_client,
    )


@inject
def main(service: Service = Provide[Container.service]):
    ...


if __name__ == '__main__':
    container = Container()
    container.config.api_key.from_env('API_KEY')
    container.config.timeout.from_env('TIMEOUT')
    container.wire(modules=[sys.modules[__name__]])

    main()  # <-- dependency is injected automatically

    with container.api_client.override(mock.Mock()):
        main()  # <-- overridden dependency is injected automatically

More samples

What's the difference between this Python project and similar ones?

1. Fast. Implemented in Cython.
2. Documentation. Has up-to-date documentation and tutorials.
3. 300 000 downloads monthly. https://pepy.tech/project/dependency-injector
4. First positions in Google search results for "python dependency injection" query. https://www.google.com/search?q=python+dependency+injection

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