---
id: uncalled-for
version: "0.4.0"
license: # Released under MIT License Copyright (c) 2025 Chris Guidry. Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the… (full text in the JSON record)
license_treatment: permissive
maintenance: active
---

# uncalled-for — Async dependency injection for Python functions

License: permissive · Maintenance: active · Popularity: top 1,000 on PyPI

## Install

pip install uncalled-for
uv add uncalled-for
poetry add uncalled-for

## Description

# uncalled-for

Async dependency injection for Python functions.

Declare what your function needs as parameter defaults. They show up resolved
when the function runs. No ceremony, no container, no configuration.

```python
from uncalled_for import Depends

async def get_db():
    db = await connect()
    try:
        yield db
    finally:
        await db.close()

async def handle_request(db: Connection = Depends(get_db)):
    await db.execute("SELECT 1")
```

## Features

- **Zero dependencies** — standard library only
- **Async-native** — built on `AsyncExitStack` and `ContextVar`
- **Context manager lifecycle** — sync and async generators get proper cleanup
- **Nested dependencies** — dependencies can depend on other dependencies
- **Caching** — each dependency resolves once per call, even if referenced multiple times
- **Call arguments** — a factory can reference the arguments of the call it serves

## Call arguments

A factory sometimes needs a value from the call itself, not from another
dependency. `CallArgument` declares that reference:

```python
from uncalled_for import CallArgument, Depends

def load_user(user_id: str = CallArgument()) -> User:
    return...

## AI interpretation — verify before relying

Async dependency injection for Python functions using parameter defaults, with zero external dependencies and built-in support for context manager lifecycles and nested dependency resolution.

Verdict: A lightweight, actively maintained async dependency injection library with zero external dependencies and permissive MIT licensing. Best suited for async Python projects needing declarative dependency resolution; Alpha status and small community (15 stars) suggest evaluating for production use with caution.

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