py-dependency-injection 1.0.0b3

A dependency injection library for Python.

py-dependency-injection

A dependency injection library for Python.

Why py-dependency-injection?

py-dependency-injection is inspired by the built-in dependency injection system in ASP.NET Core. It provides a lightweight and extensible way to manage dependencies in Python applications. By promoting constructor injection and supporting scoped lifetimes, it encourages clean architecture and makes testable, maintainable code the default.

Features

• Scoped Registrations: Define the lifetime of your dependencies as transient, scoped, or singleton.
• Constructor Injection: Automatically resolve and inject dependencies when creating instances.
• Method Injection: Inject dependencies into methods using a simple decorator.
• Factory Functions: Register factory functions, classes, or lambdas to create dependencies.
• Instance Registration: Register existing instances as dependencies.
• Tag-Based Registration and Resolution: Organize and resolve dependencies based on tags.
• Multiple Containers: Support for using multiple dependency containers.

Compatibility

The library is compatible with the following Python versions:

• 3.7, 3.8, 3.9, 3.10, 3.11, 3.12, 3.13

Installation

$ pip install py-dependency-injection

Quick Start

Here's a quick example to get you started:

from dependency_injection.container import DependencyContainer

# Define an abstract payment gateway interface
class PaymentGateway:
    def charge(self, amount: int, currency: str):
        raise NotImplementedError()

# A concrete implementation using Stripe
class StripeGateway(PaymentGateway):
    def charge(self, amount: int, currency: str):
        print(f"Charging {amount} {currency} using Stripe...")

# A service that depends on the payment gateway
class CheckoutService:
    def __init__(self, gateway: PaymentGateway):
        self._gateway = gateway

    def checkout(self):
        self._gateway.charge(2000, "USD")  # e.g. $20.00

# Get the default dependency container
container = DependencyContainer.get_instance()

# Register StripeGateway as a singleton (shared for the app's lifetime)
container.register_singleton(PaymentGateway, StripeGateway)

# Register CheckoutService as transient (new instance per resolve)
container.register_transient(CheckoutService)

# Resolve and use the service
checkout = container.resolve(CheckoutService)
checkout.checkout()

Documentation

For more advanced usage and examples, please visit our readthedocs page.

License

py-dependency-injection is released under the GPL 3 license. See LICENSE for more details.

Source Code

You can find the source code for py-dependency-injection on GitHub.

Release Notes

Latest: 1.0.0-beta.3 (2025-06-14)

• Enhancement: Added DependencyContainer.configure_default_container_name(...) to support container isolation in parallel tests, even when application code uses a single shared container via DependencyContainer.get_instance().
• Enhancement: Added DependencyContainer.clear_instances() as a clean alternative to manually resetting _instances during test teardown.

➡️ Full changelog: GitHub Releases