A Very Simple Python Dependency Injector
Use pip!
pip install pychkari
Pychkari (pronounced peach kaa ree) is a simple dependency injector for Python. It is intended to be a no-fuss library that depends on as few packages as possible and just works.
This example should get us started!
# Class definitions for reference
class A:
def __init__(self,
depOne, # casing support
second_dep: "DepTwo", # annotations support
const_dep=3): # not a dependency
self.dep1 = depOne
self.dep2 = second_dep
self.const_d = const_dep
class DepOne:
def __init__(self):
self.timestamp = datetime.now()
class DepTwo:
def __init__(self):
self.timestamp = datetime.now()
class B:
def __init__(self, a, dep_one):
self.a = a
self.dep1 = dep_one
# registration
container = Container.instance()
container.register("MyAwesomeService", B) # explicitly named registration
container.register_class(A) # service name "A" implicit
container.register_class(DepOne) # service name "DepOne" implicit
container.register_class(DepTwo) # service name "DepTwo" implicit
# instantiation
service = container.get("MyAwesomeService") # creates instance of "B" with dependencies injected
Pychkari is barely a few kilobytes. It doesn't have third party dependencies. Just drop it into your project and run with it.
Pychkari doesn't require you to change your code. As long as common Python conventions are followed, your existing code just works!
No fancy annotations, no decorations, no commitments. You're free to mix and match with any other framework.
This chart should tell you how dependencies are resolved:
| Dependency | Resolved Service Name |
|---|---|
| underscore_case | UnderscoreCase |
| camelCase | CamelCase |
| PascalCase | PascalCase |
| my_Weird_case | MyWeirdCase |
| my_service:HttpClient | HttpClient |
Well, sort of! If the conventions don't satisfy your complex naming schemes, you can always make the names explicit by annotating the dependencies.
For example, client:"MyService" will inject and instance of MyService in place of client.