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FastDI Documentation

FastDI pairs a Rust core with a lightweight Python API to provide fast, explicit dependency injection. Use it to wire sync or async providers, apply scopes, and observe resolution without ceremony.

What You Get

  • Plan compilation with cycle detection and cached execution
  • Decorators for sync/async functions and methods
  • Scopes for transient, singleton, and per-request lifetimes
  • Layered overrides to swap providers safely
  • Hooks that report timings and cache hits

Requirements: Python 3.9+ and a stable Rust toolchain.

Quick Start

pip install fastdi-core
# or set up a local dev environment:
uv sync --dev
uv run maturin develop -r -q
uv run python -m examples.basic

from typing import Annotated, Protocol
from fastdi import Container, Depends, provide, inject


container = Container()


class Service(Protocol):
    def ping(self) -> dict: ...


@provide(container, singleton=True)
def get_db() -> dict:
    return {"db": "connection"}


@provide(container)
def get_service(db: Annotated[dict, Depends(get_db)]) -> Service:
    class Impl:
        def __init__(self, source):
            self._source = source
        def ping(self) -> dict:
            return {"ok": True, "via": self._source["db"]}
    return Impl(db)


@inject(container)
def handler(service: Annotated[Service, Depends(get_service)]):
    return service.ping()


print(handler())

Where to Go Next