2nd/10_Wiki/Topics/Domain_Programming/Programming & Language/스파게티 코드 (Spaghetti Code).md

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id	title	category	status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	verification_status	tags	raw_sources	last_reinforced	github_commit	tech_stack
wiki-2026-0508-스파게티-코드-spaghetti-code	스파게티 코드 (Spaghetti Code)	10_Wiki/Topics	verified	self	spaghetti code tangled code	none	A	0.95	applied	anti-pattern code-quality refactoring		2026-05-10	pending	language framework any any

스파게티 코드 (Spaghetti Code)

매 한 줄

"매 control flow 가 noodle 처럼 entangled 되어 trace 불가". 매 unstructured GOTO · deeply nested conditions · global state mutation · circular dependency 가 만든 maintenance nightmare. 매 SOLID 위반 의 most visible symptom.

매 핵심

매 증상

• Tangled control flow: 함수 한 개가 500+ lines, nested if 5+.
• Global state: any 함수 가 any 변수 mutate.
• Circular dep: A→B→C→A.
• Magic numbers/strings: meaning unclear.
• Copy-paste: same logic in 7 places.

매 원인

• Time pressure → "just make it work".
• No code review → drift 누적.
• Premature optimization → unnecessary complexity.
• Lack of architecture → ad-hoc additions.

매 응용 (refactor 전략)

1. Extract method · extract class.
2. Replace conditional with polymorphism.
3. Introduce parameter object.
4. Strangler fig migration.

💻 패턴

Before (spaghetti)

function processOrder(o: any) {
  if (o.type == "A") {
    if (o.user.isVip) {
      o.discount = 0.2;
      if (o.country == "KR") o.tax = 0.1;
      else if (o.country == "US") o.tax = 0.07;
      // ... 200 more lines
    }
  }
}

After (refactored)

type Order = { type: OrderType; user: User; country: Country; items: Item[] };

const discountStrategy: Record<OrderType, (u: User) => number> = {
  A: u => u.isVip ? 0.2 : 0.05,
  B: () => 0.1,
};

const taxRate: Record<Country, number> = { KR: 0.1, US: 0.07, JP: 0.08 };

function processOrder(o: Order) {
  const discount = discountStrategy[o.type](o.user);
  const tax = taxRate[o.country];
  return finalizePricing(o, discount, tax);
}

Replace conditional with polymorphism

abstract class Payment {
  abstract process(amount: number): Promise<void>;
}
class CardPayment extends Payment { async process(a: number) { /* card */ } }
class CryptoPayment extends Payment { async process(a: number) { /* btc */ } }

Extract method

// before: 1 huge function
// after: 5 small functions, each <20 lines, single responsibility
function checkout(cart: Cart) {
  validateCart(cart);
  const total = calculateTotal(cart);
  const tax = applyTax(total, cart.country);
  return submitPayment(cart.user, total + tax);
}

Detect with cyclomatic complexity

npx eslint . --rule 'complexity: ["error", 10]'
npx code-complexity ./src --max 10

매 결정 기준

상황	Approach
Function > 50 lines	extract method
Nested if > 3	early return / strategy map
Same logic in 3+ places	DRY (extract function)
Module circular dep	dependency inversion
Cyclomatic > 10	refactor split

기본값: function 30 lines 미만 · cyclomatic 10 미만 · single responsibility.

🔗 Graph

• 부모: SOLID 원칙 · 관심사의 분리 (Separation of Concerns)
• Adjacent: 단일 책임 원칙 (SRP) · 기본 타입에의 집착 (Primitive Obsession)

🤖 LLM 활용

언제: legacy code refactor · cyclomatic 감소 제안 · extract method 자동화. 언제 X: domain semantics 가 unclear → human review 필수.

❌ 안티패턴

• Big rewrite: incremental refactor 가 safe.
• Refactor without tests: regression 보장 없음.
• Premature abstraction: 2번째 use case 까지 기다림 (rule of three).

🧪 검증 / 중복

• Verified (Fowler "Refactoring" · Martin "Clean Code").
• 신뢰도 A.

🕓 Changelog

날짜	변경
2026-05-08	Phase 1
2026-05-10	Manual cleanup — spaghetti code refactor 패턴