---
id: python-encapsulation
title: "Python Encapsulation"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["name mangling", "private properties", "protected properties", "파이썬 캡슐화"]
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: ["python", "programming", "w3schools", "encapsulation", "private", "name-mangling"]
raw_sources: ["https://www.w3schools.com/python/python_encapsulation.asp"]
applied_in: []
github_commit: ""
---

# [[Python Encapsulation]]

## 🎯 한 줄 통찰 (One-line insight)
Python has no true private access control — double-underscore "private" properties are just name-mangled to `_ClassName__prop` internally, still technically accessible from outside if you know the mangled name, which is why it's a convention backed by tooling, not a hard security boundary. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Encapsulation** — keeping data and methods together in a class while controlling external access; protects against accidental changes. [S1]
- **Private properties (`__` prefix)** — cannot be accessed directly from outside the class. [S1]
- **Getter method** — a method that returns a private property's value. [S1]
- **Setter method** — a method that sets/validates a private property's value. [S1]
- **Protected properties (`_` prefix)** — a convention only; Python does NOT enforce this restriction. [S1]
- **Private methods (`__` prefix)** — same restriction as private properties; can only be called from within the class. [S1]
- **Name mangling** — Python internally renames `__age` to `_ClassName__age`; this is HOW "private" is implemented. [S1]

## 🧩 추출된 패턴 (Extracted patterns)
- **Name mangling reveals private isn't truly private** — `p1._Person__age` still works and accesses the "private" value directly — Python's encapsulation is a naming convention enforced by mangling, not a hard access-control mechanism like in some other languages. [S1]
- **Getter+setter enables validation** — a setter like `set_age()` can reject invalid values (`if age > 0: ...`) at the point of mutation, something direct attribute assignment can't do. [S1]

## 📖 세부 내용 (Details)
- Private property (inaccessible directly): `class Person: def __init__(self, name, age): self.name = name; self.__age = age` — `p1.__age` errors. [S1]
- Getter: `def get_age(self): return self.__age`. [S1]
- Setter with validation: `def set_age(self, age): if age > 0: self.__age = age else: print("Age must be positive")`. [S1]
- Protected (convention only): `self._salary = salary` — accessible but discouraged. [S1]
- Private method: `def __validate(self, num): ...` — callable only internally. [S1]
- Name mangling revealed: `print(p1._Person__age)` — works, but not recommended. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
- **"Private"가 진짜 비공개가 아님**: 네임 맹글링된 이름(`_ClassName__prop`)으로 여전히 접근 가능하다는 점이 소스에서 명시적으로 경고됨 — "not recommended"라고 언급하지만 기술적으로는 우회 가능. [S1]

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — Student 클래스의 성적 검증(`set_grade`)처럼 값 검증이 필요한 속성에 표준적으로 쓰인다. [S1]

## 💻 코드 패턴 (Code patterns)
Getter/setter with validation (Python):
```python
class Person:
    def __init__(self, name, age):
        self.name = name
        self.__age = age
    def get_age(self):
        return self.__age
    def set_age(self, age):
        if age > 0:
            self.__age = age
        else:
            print("Age must be positive")
```

## ✅ 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:** [[Python Tutorial]]
- **관련 개념:** [[Python Class Properties]], [[Python Class Methods]]
- **참조 맥락:** 데이터 보호/검증이 필요한 속성에 사용 — Python의 "private"은 관례일 뿐 강제되지 않음에 유의.

## 📚 출처 (Sources)
- [S1] W3Schools — Python Encapsulation — https://www.w3schools.com/python/python_encapsulation.asp

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