A dependency injection library, aimed for the least amount of magic
Project description
deadsimple
A dependency injection library for python, aimed for the least amount of magic.
Heavily influenced by FastAPI's dependency injection classes and logic.
Simple Example
from dataclasses import dataclass
from deadsimple import Depends, resolve
@dataclass
class DepA():
dep_b: DepB
@dataclass
class DepB():
value: str
def get_dep_b() -> DepB:
return DepB(value="some val")
def get_dep_a(dep_b: DepB = Depends(get_dep_b)) -> DepA:
return DepA(dep_b=dep_b)
my_a = resolve(get_dep_a)
assert my_a.dep_b.value == "some val"
Dependencies will instantiate once per factory for each call to resolve
.
@dataclass
class DepC():
dep_a: DepA
dep_b: DepB
def get_dep_c(
dep_a: DepA = Depends(get_dep_a),
dep_b: DepB = Depends(get_dep_b),
) -> DepC:
return DepC(dep_a=dep_a, dep_b=dep_b)
my_c = resolve(get_dep_c)
assert my_c.dep_b is my_c.dep_a.dep_b
For Singleton use lru_cache or cache from functools
from functools import lru_cache
# or from functools import cache if you're 3.9+
@dataclass
class Singleton():
pass
@dataclass
class NotSingleton():
singleton_dep: Singleton
@lru_cache
def get_singleton() -> Singleton:
return Singleton()
def get_not_singleton(singleton: Singleton = Depends(get_singleton)) -> NotSingleton:
return NotSingleton(singleton_dep=singleton)
not_singleton_a = resolve(get_not_singleton)
not_singleton_b = resolve(get_not_singleton)
assert not_singleton_a is not not_singleton_b
assert not_singleton_a.singleton_dep is not_singleton_b.singleton_dep
Override dependencies:
override_dep_b = DepB(value="some other val")
my_a = resolve(get_dep_a, overrides={get_dep_b: override_dep_b})
assert my_a.dep_b.value == "some other val"
Installing
pip install deadsimple
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