Pychkari

A Very Simple Python Dependency Injector

Installation

Use pip!

pip install pychkari

Overview

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

Features

Lightweight

Pychkari is barely a few kilobytes. It doesn't have third party dependencies. Just drop it into your project and run with it.

Zero Commitment

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:

Extensible

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.