Design Patterns MCP Server

{ "id": "domain-driven-design", "name": "Domain-Driven Design", "category": "Architectural", "description": "Focuses on modeling complex business domains through ubiquitous language", "when_to_use": "Complex business domains\nLarge teams\nLong-term projects", "benefits": "Business alignment\nMaintainable code\nTeam communication\nDomain focus", "drawbacks": "High learning curve\nInitial overhead\nRequires domain expertise", "use_cases": "Enterprise software\nFinancial systems\nHealthcare applications", "complexity": "High", "tags": [ "domain-modeling", "ubiquitous-language", "bounded-context" ], "examples": { "typescript": { "language": "typescript", "code": "// DDD: model complex business domains\n\n// Value Object (immutable)\nclass Money {\n constructor(\n public readonly amount: number,\n public readonly currency: string\n ) {\n if (amount < 0) throw new Error('Amount cannot be negative');\n }\n \n add(other: Money): Money {\n if (this.currency !== other.currency) {\n throw new Error('Currency mismatch');\n }\n return new Money(this.amount + other.amount, this.currency);\n }\n}\n\n// Entity (has identity)\nclass Product {\n constructor(\n public readonly id: string,\n public name: string,\n public price: Money\n ) {}\n}\n\n// Aggregate Root (consistency boundary)\nclass Order {\n private items: Map<string, { product: Product, quantity: number }> = new Map();\n \n constructor(\n public readonly id: string,\n public status: 'pending' | 'completed' = 'pending'\n ) {}\n \n addItem(product: Product, quantity: number) {\n if (this.status === 'completed') {\n throw new Error('Cannot modify completed order');\n }\n this.items.set(product.id, { product, quantity });\n }\n \n getTotal(): Money {\n let total = new Money(0, 'USD');\n for (const { product, quantity } of this.items.values()) {\n const itemTotal = new Money(product.price.amount * quantity, product.price.currency);\n total = total.add(itemTotal);\n }\n return total;\n }\n \n complete() {\n if (this.items.size === 0) {\n throw new Error('Cannot complete empty order');\n }\n this.status = 'completed';\n }\n}\n\n// Repository (aggregate persistence)\ninterface OrderRepository {\n save(order: Order): Promise<void>;\n findById(id: string): Promise<Order | null>;\n}\n\n// Usage: express business rules in code\nconst order = new Order('order-1');\norder.addItem(new Product('p1', 'Laptop', new Money(999, 'USD')), 1);\norder.complete();" } } }