Complementary extensions for Microsoft.Extensions.DependencyInjection that enable advanced service composition and extensibility.

Overview

This library complements Microsoft.Extensions.DependencyInjection with capabilities not provided out of the box. It focuses on service composition and extensibility so you can layer cross-cutting concerns (logging, caching, validation, retries, metrics) onto existing registrations without changing their implementations.

Installation

dotnet add package geoder101.Microsoft.Extensions.DependencyInjection

Quick Start

Basic Decorator

using Microsoft.Extensions.DependencyInjection;

var services = new ServiceCollection();

// Register your service
services.AddTransient<INotificationService, EmailNotificationService>();

// Decorate it with logging
services.Decorate<INotificationService, LoggingNotificationDecorator>();

var provider = services.BuildServiceProvider();
var notificationService = provider.GetRequiredService<INotificationService>();
// Returns LoggingNotificationDecorator wrapping EmailNotificationService

Decorator with Factory

services.AddScoped<IOrderProcessor, OrderProcessor>();

// Use factory to access IServiceProvider
services.Decorate<IOrderProcessor>((provider, inner) =>
{
    var logger = provider.GetRequiredService<ILogger<OrderProcessorDecorator>>();
    return new OrderProcessorDecorator(inner, logger);
});

Chaining Multiple Decorators

services.AddTransient<ICalculator, Calculator>();

// Add multiple decorators - they wrap in order
services.Decorate<ICalculator, CachingCalculatorDecorator>();
services.Decorate<ICalculator, LoggingCalculatorDecorator>();
services.Decorate<ICalculator, ValidationCalculatorDecorator>();

// Result: ValidationCalculatorDecorator -> LoggingCalculatorDecorator -> CachingCalculatorDecorator -> Calculator

Use Cases

The decorator pattern is ideal for adding cross-cutting concerns to your services:

• Logging - Track method calls, parameters, and results
• Caching - Add response caching to expensive operations
• Validation - Validate inputs before calling the actual service
• Retry Logic - Add resilience with automatic retries
• Performance Monitoring - Track execution time and metrics
• Authorization - Add security checks before method execution

Documentation

📚 Decorator Pattern Guide - Comprehensive documentation including:

• Complete API reference
• Real-world examples (logging, caching, retry, validation, metrics)
• Service lifetime behavior
• Best practices and common patterns
• Troubleshooting guide

Project Structure

DependencyInjection.Microsoft/
├── src/
│   ├── DependencyInjection.Microsoft/          # Main library
│   └── DependencyInjection.Microsoft.UnitTests/ # Unit tests
├── docs/
│   └── Decorator.md                             # Detailed documentation
└── README.md                                    # This file

Contributing

Contributions are welcome! Please feel free to submit issues or pull requests.

License

This project is licensed under the MIT License - see the LICENSE.txt file for details.

Co-authored with Artificial Intelligence

This repository is part of an ongoing exploration into human-AI co-creation.
The code, comments, and structure emerged through dialogue between human intent and LLM reasoning — reviewed, refined, and grounded in human understanding.