2nd/10_Wiki/Topics/Domain_Programming/Topic_Python/Python_Booleans.md

id, title, category, status, verification_status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, created_at, updated_at, review_reason, merge_history, tags, raw_sources, applied_in, github_commit

id	title	category	status	verification_status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	created_at	updated_at	review_reason	merge_history	tags	raw_sources	applied_in	github_commit
python-booleans	Python Booleans	Programming_Language	draft	conceptual		bool() truthiness 파이썬 불리언		B	0.9	2026-07-04	2026-07-04			python programming w3schools boolean truthiness	https://www.w3schools.com/python/python_booleans.asp

Python Booleans

🎯 한 줄 통찰 (One-line insight)

Almost every Python value is truthy by default — only a small, fixed set (empty collections, 0, "", None, False, and objects whose __len__ returns 0) evaluates to False. [S1]

🧠 핵심 개념 (Core concepts)

• Boolean — represents one of two values: True or False. [S1]
• bool() function — evaluates any value/variable and returns True or False. [S1]
• Most values are True — any non-empty string, any non-zero number, any non-empty list/tuple/set/dict. [S1]
• Falsy exceptions — (), [], {}, "", 0, None, False. [S1]
• Custom falsy objects — an object from a class whose __len__ returns 0 (or False) also evaluates to False. [S1]
• Functions can return booleans — including built-ins like isinstance(). [S1]

🧩 추출된 패턴 (Extracted patterns)

• __len__-based falsiness — Python's truthiness protocol extends to custom classes via __len__, meaning "empty-like" custom objects behave like empty built-in collections. [S1]

📖 세부 내용 (Details)

• Comparison expressions return booleans: print(10 > 9); print(10 == 9); print(10 < 9). [S1]
• Truthy check: bool("Hello") # True, bool(15) # True. [S1]
• Falsy check: bool(False); bool(None); bool(0); bool(""); bool(()); bool([]); bool({}). [S1]
• Custom falsy via __len__: [S1]

class myclass():
    def __len__(self):
        return 0
myobj = myclass()
print(bool(myobj))  # False

• isinstance() returns a boolean: print(isinstance(x, int)). [S1]

⚖️ 모순 및 업데이트 (Contradictions & updates)

소스에서 모순되는 정보는 발견되지 않음.

🛠️ 적용 사례 (Applied in summary)

현재 발견된 실제 적용 사례가 없습니다 — if 조건문/논리 연산자 챕터 전체가 이 불리언 평가 규칙을 전제로 한다. [S1]

💻 코드 패턴 (Code patterns)

Custom class controlling its own truthiness (Python):

class myclass():
    def __len__(self):
        return 0

myobj = myclass()
print(bool(myobj))  # False

✅ 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 If Else, Python Operators Logical, Python Operators Comparison
• 참조 맥락: 조건문/논리 연산의 기초 — if 문/while 루프의 조건 평가 방식을 정의.

📚 출처 (Sources)

• [S1] W3Schools — Python Booleans — https://www.w3schools.com/python/python_booleans.asp

📝 변경 이력 (Change history)

• 2026-07-04: Initial draft synthesized from the W3Schools "Python Booleans" page (Astra wiki-curation, P-Reinforce v3.1 format).