Initial Commit

DependencyInjection/.gitignore

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+# dependencies (bun install)
+node_modules
+
+# output
+out
+dist
+*.tgz
+
+# code coverage
+coverage
+*.lcov
+
+# logs
+logs
+_.log
+report.[0-9]_.[0-9]_.[0-9]_.[0-9]_.json
+
+# dotenv environment variable files
+.env
+.env.development.local
+.env.test.local
+.env.production.local
+.env.local
+
+# caches
+.eslintcache
+.cache
+*.tsbuildinfo
+
+# IntelliJ based IDEs
+.idea
+
+# Finder (MacOS) folder config
+.DS_Store

DependencyInjection/README.md

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+# Simple Dependency Injection Container
+
+A learning project to understand how Dependency Injection works by building one from scratch.
+
+Inspired by the Phenix RTS platform's DI system.
+
+## Learning Goals
+
+1. Understand how DI containers resolve dependencies
+2. Learn about different lifecycle patterns (singleton, transient, factory)
+3. Understand circular dependency detection
+4. Learn about provider patterns
+5. Understand type registration and resolution
+
+## Steps
+
+We'll build this incrementally:
+
+1. **Step 1**: Basic container with manual registration
+2. **Step 2**: Constructor injection
+3. **Step 3**: Singleton vs Transient lifecycles
+4. **Step 4**: Circular dependency detection
+5. **Step 5**: Provider pattern
+6. **Step 6**: Named registrations
+7. **Step 7**: Configuration-driven DI (like Phenix's di.json)
+
+## Running the Examples
+
+```bash
+# Step 1 - Basic
+node step1-basic.js
+
+# Step 2 - Constructor Injection
+node step2-constructor-injection.js
+
+# Step 3 - Lifecycles
+node step3-lifecycles.js
+
+# Step 4 - Circular Dependencies
+node step4-circular-deps.js
+
+# Step 5 - Providers
+node step5-providers.js
+
+# Step 6 - Named Registrations
+node step6-named.js
+
+# Step 7 - Configuration
+node step7-config.js
+```
+
+## Key Concepts
+
+### Dependency Injection
+
+Instead of creating dependencies inside a class, they are "injected" from outside.
+
+### Inversion of Control (IoC)
+
+The container controls object creation and lifecycle, not your code.
+
+### Service Locator vs DI
+
+DI is better because dependencies are explicit in constructor signatures.
+
+## Architecture
+
+```
+Container
+├── Registry (stores type registrations)
+├── Resolver (resolves dependencies)
+├── Lifecycle Manager (handles singleton/transient)
+└── Provider System (custom creation logic)
+```

DependencyInjection/package.json

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+{
+  "name": "dependencyinjection",
+  "module": "index.ts",
+  "type": "module",
+  "private": true,
+  "scripts": {
+    "step:1": "bun run src/Step1",
+    "step:2": "bun run src/Step2"
+  },
+  "devDependencies": {
+    "@types/bun": "latest",
+    "prettier": "3.6.2"
+  },
+  "peerDependencies": {
+    "typescript": "5.9,3"
+  }
+}

DependencyInjection/tsconfig.json

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+{
+  "compilerOptions": {
+    // Environment setup & latest features
+    "lib": ["ESNext"],
+    "target": "ESNext",
+    "module": "Preserve",
+    "moduleDetection": "force",
+    "jsx": "react-jsx",
+    "allowJs": true,
+
+    // Bundler mode
+    "moduleResolution": "bundler",
+    "allowImportingTsExtensions": true,
+    "verbatimModuleSyntax": true,
+    "noEmit": true,
+
+    // Best practices
+    "strict": true,
+    "skipLibCheck": true,
+    "noFallthroughCasesInSwitch": true,
+    "noUncheckedIndexedAccess": true,
+    "noImplicitOverride": true,
+
+    // Some stricter flags (disabled by default)
+    "noUnusedLocals": false,
+    "noUnusedParameters": false,
+    "noPropertyAccessFromIndexSignature": false
+  }
+}