wd-di 0.2.9

.NET Core Dependency Injection for Python

WD-DI

.NET Style Dependency Injection for Python

WD-DI brings the robust and flexible dependency injection patterns of .NET to your Python applications, with no external library dependencies, just Python's standard library.

Full documentation can be found at https://whiteducksoftware.github.io/wd-di/ (or in the /docs directory).

For beginners, the Core Concepts and Tutorials sections in the documentation are a great place to start to understand not just how to use DI, but why it's beneficial!

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Why WD-DI? 🤔

• Simplified Dependency Management: Effortlessly manage object creation and lifecycles.
• Enhanced Testability: Easily mock dependencies for robust unit tests.
• Modular Architecture: Build loosely coupled, maintainable, and scalable applications.
• Familiar Patterns: Leverage .NET-inspired DI concepts like service lifetimes (Singleton, Scoped, Transient), constructor injection, and the Options pattern for configuration.
• Pythonic and Lightweight: Clean, intuitive API that integrates smoothly into your Python projects.

✅ Feature	WD-DI	Typical alternatives
Pure-stdlib (zero runtime deps)	✔	✘ pull in pydantic / C-extensions
.NET-style lifetimes Transient • Singleton • Scoped (+ auto-dispose)	✔	Scoped rarely supported
Strongly-typed Options binding from dict/JSON/env → dataclass	✔	Dicts or manual parsing
Middleware pipeline bundled & DI-aware (async-first)	✔	None ship a generic pipeline
Decorator-based registration tied to your ServiceCollection (no globals)	✔	Global singletons or meta-classes
Thread-safe circular-dependency detection via ContextVar	✔	Simple set → race-prone
Full IDE type inference for get_service()	✔	Returns Any / needs cast()
Lean & readable (~1.4 k LOC + robust test suite)	✔	wtf am I reading

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Installation 📦

pip install wd-di

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Quick Example: The Power of WD-DI 🚀

Experience clean, decoupled code with intuitive type-hinted dependency resolution:

from wd.di import ServiceCollection

services = ServiceCollection()

# Define interfaces and implementations
class IEmailService:
    def send_email(self, to: str, subject: str, body: str) -> None:
        pass

class EmailService(IEmailService):
    def send_email(self, to: str, subject: str, body: str) -> None:
        print(f"\nSending email to {to}")
        print(f"Subject: {subject}")
        print(f"Body: {body}")
        print("Email sent successfully\n")

# UserService depends on IEmailService
class UserService:
    def __init__(self, email_service: IEmailService):
        self.email_service = email_service

    def notify_user(self, user_id: str, message: str) -> None:
        self.email_service.send_email(f"user{user_id}@example.com", "Notification", message)

# Register services
services.add_singleton(IEmailService, EmailService)
services.add_singleton(UserService)

# Build provider
# Services will be resolved and injected into services 
# like EmailService into UserService
provider = services.build_service_provider()

# Get services with proper type hints
email_service = provider.get_service(IEmailService)
user_service = provider.get_service(UserService)

# IDE will provide code completion for these methods
# No need to cast or use Any
email_service.send_email("[e-mail]", "Test", "Hello")
user_service.notify_user("123", "Welcome!")

Dive into the full documentation to explore service lifetimes, configuration, middleware, and more!

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Contributing 🤝

Contributions are welcome! Please see the main documentation site for details on how to contribute, report issues, or request features.

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License 📜

This project is licensed under the MIT License. See the LICENSE file for details.