---
id: php-oop-access-modifiers
title: "PHP OOP Access Modifiers"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["public private protected", "PHP 접근 제어자"]
duplicate_of: ""
source_trust_level: "B"
confidence_score: 0.9
created_at: 2026-07-04
updated_at: 2026-07-04
review_reason: ""
merge_history: []
tags: ["php", "programming", "w3schools", "oop", "access-modifiers"]
raw_sources: ["https://www.w3schools.com/php/php_oop_access_modifiers.asp"]
applied_in: []
github_commit: ""
---

# [[PHP OOP Access Modifiers]]

## 🎯 한 줄 통찰 (One-line insight)
`protected` occupies a middle ground invisible from direct outside access, YET fully usable inside a subclass via its own method — a child class can't do `$apple->name` directly, but a method it defines (like `getType()`) CAN read `$this->name` because it executes inside the class hierarchy, not from outside it. [S1]

## 🧠 핵심 개념 (Core concepts)
- **`public`** (default if unspecified) — accessible from anywhere. [S1]
- **`protected`** — accessible within the class AND by derived (child) classes; NOT accessible directly from outside. [S1]
- **`private`** — accessible ONLY within the exact class where defined; not even child classes can access it directly. [S1]

## 📖 세부 내용 (Details)
- Public (works from outside): `class Fruit { public $name; ... } $apple = new Fruit(); $apple->name = "Apple"; // OK`. [S1]
- Private (fails from outside): `class Fruit { private $name; ... } $apple->name = "Apple"; // Error`. [S1]
- Protected (fails from outside): `class Fruit { protected $name; ... } $apple->name = "Apple"; // Error`. [S1]
- Protected accessible via a child class's own method: `class Fruit { protected $name; public function setType($name) { $this->name = $name; } } class Apple extends Fruit { public function getType() { echo "Name: " . $this->name . "."; } } $apple = new Apple(); $apple->setType("Apple"); echo $apple->getType(); // works — accessed via a method, not directly`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
- **protected의 이중적 접근성**: 외부에서 직접 접근($apple->name)은 불가하지만, 자식 클래스가 정의한 메서드 내부($this->name)에서는 접근 가능하다는 점이 예제로 명확히 대비됨. [S1]

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — Fruit→Apple 상속 구조에서 protected 속성에 자식 클래스 메서드로 접근하는 것이 캡슐화의 대표 실전 사례다. [S1]

## 💻 코드 패턴 (Code patterns)
Protected property accessible via a child class's method, not directly (PHP):
```php
class Fruit {
    protected $name;
    public function setType($name) { $this->name = $name; }
}
class Apple extends Fruit {
    public function getType() { echo "Name: " . $this->name . "."; }
}
$apple = new Apple();
$apple->setType("Apple");
echo $apple->getType(); // works
// echo $apple->name; // Error: cannot access protected property directly
```

## ✅ 검증 상태 및 신뢰도
- **상태:** draft
- **검증 단계:** conceptual
- **출처 신뢰도:** B (W3Schools — widely used educational reference, not a primary standards body)
- **신뢰 점수:** 0.90
- **중복 검사 결과:** 신규 생성 (New discovery)

## 🔗 지식 그래프 (Knowledge Graph)
- **상위/루트:** [[PHP Tutorial]]
- **관련 개념:** [[PHP OOP Destructor]], [[PHP OOP Inheritance]]
- **참조 맥락:** 접근 제어의 기초 — 상속(Inheritance) 챕터로 직접 이어짐.

## 📚 출처 (Sources)
- [S1] W3Schools — PHP OOP - Access Modifiers — https://www.w3schools.com/php/php_oop_access_modifiers.asp

## 📝 변경 이력 (Change history)
- 2026-07-04: Initial draft synthesized from the W3Schools "PHP OOP Access Modifiers" page (Astra wiki-curation, P-Reinforce v3.1 format).
