fundi 0.0.5

Dependency injection library

# FunDI

Solution for problem no one had before

Fun stays for function(or for fun if you wish) and DI for Dependency Injection

This library provides fast(to write!) and convenient(to use!) Dependency Injection for functional programming on python.

No more words, let's try!

from contextlib import ExitStack
from typing import Generator, Any

from fundi import from_, inject, scan

def require_database_session(database_url: str) -> Generator[str, Any]:
    print(f"Opened database session at {database_url = }")
    yield "database session"
    print("Closed database session")


def require_user(session: str = from_(require_database_session)) -> str:
    return "user"


def application(user: str = from_(require_user), session: str = from_(require_database_session)):
    print(f"Application started with {user = }")


with ExitStack() as stack:
    inject({"database_url": "postgresql://kuyugama:insecurepassword@localhost:5432/database"}, scan(application), stack)

Async? YES!!!

import asyncio
from contextlib import AsyncExitStack
from typing import AsyncGenerator, Any

from fundi import from_, ainject, scan

async def require_database_session(database_url: str) -> AsyncGenerator[str, Any]:
    print(f"Opened database session at {database_url = }")
    yield "database session"
    print("Closed database session")


async def require_user(session: str = from_(require_database_session)) -> str:
    return "user"


async def application(user: str = from_(require_user), session: str = from_(require_database_session)):
    print(f"Application started with {user = }")


async def main():
    async with AsyncExitStack() as stack:
        await ainject({"database_url": "postgresql://kuyugama:insecurepassword@localhost:5432/database"}, scan(application), stack)


asyncio.run(main())

Resolve dependencies by type

It's simple! Use from_ on type annotation

from contextlib import ExitStack

from fundi import from_, inject, scan

class Session:
    """Database session"""

def require_user(_: from_(Session)) -> str:
    return "user"


def application(session: from_(Session), user: str = from_(require_user)):
    print(f"Application started with {user = }")
    print(f"{session = }")


with ExitStack() as stack:
    inject({"db": Session()}, scan(application), stack)

Note: while resolving dependencies by type parameter names doesn't really matter.

Utilities

• fundi.order - returns order in which dependencies will be resolved
• fundi.tree - returns dependency resolving tree