2nd/10_Wiki/Topics/Domain_Programming/Architecture/Object-Oriented-Programming.md

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

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-object-oriented-programming	Object-Oriented Programming (OOP)	10_Wiki/Topics	verified	self	OOP Object Oriented Programming 객체지향 객체지향 프로그래밍	none	A	0.95	applied	oop programming-paradigm design architecture		2026-05-10	pending	language framework java-typescript-cpp multi

Object-Oriented Programming (OOP)

매 한 줄

"매 data + behavior를 object로 묶고, polymorphism으로 동작을 추상화하는 패러다임.". Simula 67 (1967) → Smalltalk (1972) → C++ (1985) → Java (1995) → 매 mainstream. 2026 현재는 OO + FP hybrid가 dominant — Java records, Kotlin data class, TypeScript readonly class, Rust trait이 그 증거.

매 핵심

매 4 pillar

• Encapsulation: 매 internal state hide, expose behavior — private field + public method.
• Inheritance: 매 reuse + specialize — 단 favor composition over inheritance (GoF).
• Polymorphism: 매 same interface, different impl — virtual dispatch · duck typing.
• Abstraction: 매 essential 만 expose — interface · abstract class.

매 SOLID (Robert C. Martin)

• Single Responsibility — 매 class one reason to change.
• Open/Closed — 매 extend without modify.
• Liskov Substitution — 매 subtype substitutable.
• Interface Segregation — 매 small focused interfaces.
• Dependency Inversion — 매 depend on abstraction.

매 응용

1. Domain-Driven Design — Entity, Value Object, Aggregate.
2. GUI framework — Component hierarchy (React class component, Qt widget).
3. Game engine — Entity-Component-System (modern hybrid).

💻 패턴

Encapsulation — invariant 보장

public final class Money {
    private final BigDecimal amount;
    private final Currency currency;
    public Money(BigDecimal a, Currency c) {
        if (a.signum() < 0) throw new IllegalArgumentException("negative");
        this.amount = a; this.currency = c;
    }
    public Money add(Money other) {
        if (!currency.equals(other.currency))
            throw new IllegalStateException("currency mismatch");
        return new Money(amount.add(other.amount), currency);
    }
}

Polymorphism — strategy

interface Shipping {
  calculate(weight: number): number;
}
class StandardShipping implements Shipping {
  calculate(w: number) { return w * 5; }
}
class ExpressShipping implements Shipping {
  calculate(w: number) { return w * 12 + 10; }
}
function totalCost(items: Item[], shipping: Shipping): number {
  const w = items.reduce((s, i) => s + i.weight, 0);
  return items.reduce((s, i) => s + i.price, 0) + shipping.calculate(w);
}

Composition over inheritance

// BAD: deep hierarchy
class Animal {}
class Dog extends Animal {}
class FlyingDog extends Dog {} // ???

// GOOD: composition
class Animal {
  constructor(
    private mover: Movement,
    private noise: NoiseMaker,
  ) {}
  move() { return this.mover.move(); }
  speak() { return this.noise.sound(); }
}
const dog = new Animal(new Walking(), new Bark());
const bird = new Animal(new Flying(), new Chirp());

Abstract class + template method

public abstract class HttpHandler {
    public final Response handle(Request req) {
        if (!authenticate(req)) return Response.unauthorized();
        var data = process(req);
        return render(data);
    }
    protected abstract boolean authenticate(Request req);
    protected abstract Object process(Request req);
    protected Response render(Object data) {
        return Response.ok().json(data);
    }
}

Modern hybrid — record (Java 21) / data class

public record User(UserId id, Email email, String name) {
    public User {  // compact constructor
        Objects.requireNonNull(email);
        if (name.isBlank()) throw new IllegalArgumentException();
    }
    public User withName(String n) { return new User(id, email, n); }
}

Trait-based OOP (Rust)

trait Drawable {
    fn draw(&self, canvas: &mut Canvas);
    fn bounds(&self) -> Rect;
}
struct Circle { center: Point, r: f32 }
impl Drawable for Circle {
    fn draw(&self, c: &mut Canvas) { c.circle(self.center, self.r); }
    fn bounds(&self) -> Rect { Rect::around(self.center, self.r) }
}
fn render_all(shapes: &[Box<dyn Drawable>], canvas: &mut Canvas) {
    for s in shapes { s.draw(canvas); }
}

매 결정 기준

상황	Approach
Domain with complex invariants	OOP + DDD entities/VO
Pure data transformation	FP (immutable + pure functions)
Plug-in / extensibility	Interface + DI
State machine	OOP class with explicit states
Hot loop, ECS scale	Data-Oriented (avoid virtual dispatch)

기본값: hybrid OOP+FP — value objects immutable, services with interfaces, pure functions for transforms.

🔗 Graph

• 변형: Functional_Programming · Procedural-Architecture-Systems · ECS
• 응용: SOLID Principles · Polymorphism (다형성) · Object Seam (객체 접점) · Bounded_Context
• Adjacent: High-Cohesion-Low-Coupling · Dependency_Inversion_Principle · Hexagonal_Architecture_Ports_and_Adapters

🤖 LLM 활용

언제: business domain modeling, framework/library design, GUI hierarchy, plug-in architecture. 언제 X: hot numerical loop (DOD better), pure transform pipeline (FP cleaner), 1-file script.

❌ 안티패턴

• God Object: 매 모든 책임 한 class — SRP 위반.
• Anemic Domain Model: data only, behavior in service — OOP 무력화.
• Deep inheritance (4+ levels): 매 fragile base class.
• Premature interface: 매 single impl을 interface로 — YAGNI.
• Setter everywhere: 매 invariant 깨짐 — immutable + factory.

🧪 검증 / 중복

• Verified (GoF Design Patterns 1994, Martin Clean Code 2008, Evans DDD 2003, Java/Kotlin/Rust 2026 docs).
• 신뢰도 A.
• Duplicates: 객체_지향_프로그래밍(OOP).md, 객체_지향_프로그래밍_Object-Oriented_Programming,_OOP.md should redirect here.

🕓 Changelog

날짜	변경
2026-05-08	Phase 1
2026-05-10	Manual cleanup — canonical OOP doc (4 pillars + SOLID + modern hybrid)