Design Patterns MCP Server

{ "id": "data-classes", "name": "Data Classes Pattern", "category": "Creational", "description": "Immutable data containers with automatic equals, hashCode, copy, and toString methods", "when_to_use": "Value objects, DTOs, configuration objects, domain models", "benefits": "Immutability, automatic methods, concise syntax, destructuring support", "drawbacks": "Limited inheritance, no custom logic in auto-generated methods, compilation overhead", "use_cases": "API responses, configuration, domain entities, data transfer", "complexity": "Low", "tags": ["kotlin", "immutable", "value-objects", "dto", "destructuring"], "examples": { "kotlin": { "language": "kotlin", "code": "data class User(\n val id: String,\n val name: String,\n val email: String,\n val createdAt: Instant = Instant.now(),\n val isActive: Boolean = true\n)\n\n// Automatic features\ndata class Point(val x: Int, val y: Int) {\n // Custom methods allowed\n fun distanceTo(other: Point): Double {\n val dx = (x - other.x).toDouble()\n val dy = (y - other.y).toDouble()\n return sqrt(dx * dx + dy * dy)\n }\n}\n\n// Usage examples\nval user1 = User(\"1\", \"John\", \"john@example.com\")\nval user2 = user1.copy(name = \"Jane\") // Immutable update\n\n// Destructuring\nval (id, name, email, createdAt, isActive) = user1\n\n// Structural equality\nval user3 = User(\"1\", \"John\", \"john@example.com\")\nprintln(user1 == user3) // true - compares by value\n\n// Component functions\nprintln(user1.component1()) // \"1\" (id)\nprintln(user1.component2()) // \"John\" (name)\n\n// Copy with modifications\nval updatedUser = user1.copy(\n email = \"jane@example.com\",\n isActive = false\n)\n\n// Data class inheritance (limited)\nsealed class Response\n\ndata class Success<T>(val data: T) : Response()\ndata class Error(val message: String, val code: Int) : Response()\n\n// Smart casting with when\nfun handleResponse(response: Response) {\n when (response) {\n is Success -> println(\"Data: ${response.data}\")\n is Error -> println(\"Error: ${response.message}\")\n }\n}" } } }