🧪️ Configuration Is Scattered

✅ Problem Overview

When an application grows, configuration and dependency initialization often become scattered, duplicated, or inconsistent.
Manually wiring values in multiple places leads to tight coupling and reduced flexibility.

Common issues include:

• Initialization logic is duplicated and difficult to manage
• Inconsistent configuration handling across modules
• Hard to switch environments between test/staging/production

✅ Solution Overview

Use the Factory pattern to centralize configuration creation,
and the Singleton pattern to ensure consistent reuse of that configuration across the system.

Concern	Applied Pattern
Centralized configuration init	Factory
Shared access to instances	Singleton

✅ Pattern Synergy

Role	Example Implementation
Configuration source	ConfigFactory (initializer)
Shared instance	AppConfig (singleton)
Consumers	ServiceA, ServiceB

• Factory creates a single, consistent configuration structure
• Singleton ensures shared access and avoids redundant instantiation

✅ UML Class Diagram

✅ Explanation

This design separates configuration concerns from usage:

• ConfigFactory encapsulates how configuration is created and loaded (Factory)
• AppConfig is created once and shared system-wide (Singleton)
• Services depend only on the AppConfig interface, not the creation logic

This enables clean initialization and easier testing or replacement.

✅ Practical Notes

• ✅ Environment switching (dev/staging/prod) becomes easier
• ✅ Configuration can be mocked or overridden in test contexts
• ✅ Also applicable to shared resources like DB connections or auth providers

Examples:

• Wrapping .env loading into a single AppConfig class
• Injecting mock ConfigFactory in unit tests
• Managing shared configuration for internal libraries and services

✅ Summary

• Use Factory to centralize configuration creation logic
• Use Singleton to maintain a consistent, shared config instance
• Greatly improves clarity and maintainability of application setup
• Enables safe, flexible environment switching and testability

This design provides a robust foundation for scalable and reliable configuration management.