2nd/10_Wiki/Topic_Programming/Architecture/vFunction.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-vfunction	vFunction	10_Wiki/Topics	verified	self	virtual function 가상 함수 vFunction.com	none	A	0.9	applied	oop polymorphism architecture modernization		2026-05-10	pending	language framework cpp none

vFunction

매 한 줄

"매 dispatch 의 runtime 의 resolve". 매 term 의 two meanings — (1) C++ virtual function (vtable-based dynamic dispatch), (2) vFunction.com (AI-driven Java monolith → microservices modernization platform). 매 context 의 disambiguate.

매 핵심

매 (1) Virtual function (C++)

• vtable: 매 class per — function pointer table.
• vptr: 매 instance per — vtable 의 pointer.
• Dispatch: obj->fn() → obj->vptr[fn_index]() (one extra indirection).
• Cost: ~1-2 ns per call, 매 inlining 의 block.
• Override: derived class 의 same signature 의 redefine.

매 (2) vFunction.com platform

• Static + dynamic analysis: 매 Java/.NET monolith 의 scan.
• Domain extraction: AI 의 bounded context 의 cluster.
• Refactor recommendation: 매 service boundary + dead code + TCO.
• 2025 update: Claude/GPT-5 backed reasoning, 매 Spring Boot extraction template.

매 응용 (vfunc C++)

1. Strategy pattern.
2. Plugin/driver interface.
3. Mock injection 의 testing.

매 응용 (vFunction.com)

1. Legacy Java EE → microservice migration.
2. Technical debt quantification.
3. Architectural drift detection.

💻 패턴

Virtual function (modern C++20)

struct Shape {
    virtual ~Shape() = default;
    virtual double area() const = 0;       // pure virtual
};

struct Circle : Shape {
    double r;
    explicit Circle(double r) : r(r) {}
    double area() const override { return 3.14159 * r * r; }
};

double total(std::span<const std::unique_ptr<Shape>> shapes) {
    double s = 0;
    for (auto& sh : shapes) s += sh->area();   // dynamic dispatch
    return s;
}

Devirtualization hint (final)

struct FastCircle final : Shape {              // final → compiler 의 devirtualize
    double area() const override final { return 3.14; }
};

CRTP (static polymorphism, vfunc 의 X)

template<class Derived>
struct Shape {
    double area() const { return static_cast<const Derived*>(this)->area_impl(); }
};

struct Square : Shape<Square> {
    double s;
    double area_impl() const { return s * s; }   // zero overhead
};

Rust (trait object, vfunc analog)

trait Shape { fn area(&self) -> f64; }
struct Circle { r: f64 }
impl Shape for Circle { fn area(&self) -> f64 { 3.14 * self.r * self.r } }

fn total(shapes: &[Box<dyn Shape>]) -> f64 {
    shapes.iter().map(|s| s.area()).sum()  // dyn dispatch via vtable
}

vFunction.com workflow (concept)

# .vfunction/config.yaml
target: java/spring-boot
analyze:
  paths: [src/main/java]
  exclude: [test, generated]
extract:
  strategy: domain-driven
  min-cohesion: 0.7
recommendations:
  - service-boundaries
  - dead-code
  - dependency-cycles

매 결정 기준

상황	Approach
Runtime polymorphism, OOP	virtual function
Hot loop, type known	CRTP / template
Plugin boundary	virtual + dyn lib
Legacy Java refactor	vFunction.com
Greenfield modular	DDD + bounded context

기본값: virtual function 의 default OOP, CRTP 의 perf-critical.

🔗 Graph

• 부모: Object-Oriented-Programming · Polymorphism
• Adjacent: Legacy Modernization

🤖 LLM 활용

언제: legacy code 의 virtual function chain 의 analyze, 매 modernization scope 의 estimate. 언제 X: 매 micro-optimization decision (devirtualize 의 X) — 매 profiler 의 use.

❌ 안티패턴

• Virtual everything: 매 every method 의 virtual, 의 cost + 의 hard 의 reason. Final 의 default.
• Diamond inheritance: 매 multiple virtual base, 의 composition 의 prefer.
• Virtual destructor 의 forget: base class polymorphic, 의 leak.
• vFunction 의 silver bullet: tool 의 recommendation 의 blindly 의 apply, 의 domain understanding 의 first.

🧪 검증 / 중복

• Verified (ISO C++ standard, Stroustrup "Tour of C++" 3rd, vfunction.com docs 2025).
• 신뢰도 A.

🕓 Changelog

날짜	변경
2026-05-08	Phase 1
2026-05-10	Manual cleanup — full vFunction (virtual + platform) entry