iservice

Helper class to make FastAPI dependencies with ease.

Simple use

# iservice_a.py
import typing

import iservice


class ServiceA(iservice.Service, typing.Protocol):
    @staticmethod
    def send(name: str) -> None: ...


# service_a1.py
def send(name: str) -> None:
    print(f"Hello {name}")


# service_a2.py
def send(name: str) -> None:
    print(f"Greetings {name}")


# service_a.py
import iservice_a
import service_a1
import service_a2


def _welcome_user(service: iservice_a.ServiceA, name: str) -> None:
    service.send(name)

# inject will provide an inferred type that are matching the expected signature
# (str) -> None
hello = iservice.inject(_welcome_user, service_a1)
greeting = iservice.inject(_welcome_user, service_a2)

In this case, in case of incorrect calls, mypy will raise errors like:

hello(1)  # Argument 1 has incompatible type "int"; expected "str"
greeting(1)  # Argument 1 has incompatible type "int"; expected "str"