---
id: php-namespaces
title: "PHP Namespaces"
category: "Programming_Language"
status: "draft"
verification_status: "conceptual"
canonical_id: ""
aliases: ["namespace keyword", "PHP 네임스페이스"]
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", "namespaces"]
raw_sources: ["https://www.w3schools.com/php/php_namespaces.asp"]
applied_in: []
github_commit: ""
---

# [[PHP Namespaces]]

## 🎯 한 줄 통찰 (One-line insight)
`namespace` MUST be the very first statement in a PHP file — even a preceding `echo "Hello World!";` before the namespace declaration is explicitly shown as INVALID code, meaning nothing (not even innocuous output) can come before it. [S1]

## 🧠 핵심 개념 (Core concepts)
- **Namespace** — groups classes/interfaces/functions/constants under a name to prevent naming collisions (e.g., two unrelated `Table` classes — one for HTML, one for furniture). [S1]
- **Must be declared first** — `namespace Html;` must be the absolute first line of the file. [S1]
- **Nested namespaces** — `namespace Code\Html;` for further organization. [S1]
- **Accessing from outside the namespace** — requires the full qualifier: `new Html\Table();`. [S1]
- **Inside the namespace** — no qualifier needed (`new Table();`) once you've declared `namespace Html;` at the top. [S1]
- **`use ... as ...`** — creates an alias for a namespace or class, shortening repeated references. [S1]

## 📖 세부 내용 (Details)
- Declaring and using within a namespace: `namespace Html; class Table { ... } $table = new \Html\Table();`. [S1]
- Accessing from outside: `$table = new Html\Table(); $row = new Html\Row();`. [S1]
- Accessing after declaring the same namespace: `namespace Html; $table = new Table(); $row = new Row();`. [S1]
- Namespace alias: `use Html as H; $table = new H\Table();`. [S1]
- Class alias: `use Html\Table as T; $table = new T();`. [S1]

## ⚖️ 모순 및 업데이트 (Contradictions & updates)
- **네임스페이스 선언 위치의 절대적 제약**: echo 문 하나라도 namespace 선언보다 앞에 오면 무효한 코드가 된다는 점이 명시적으로 경고됨. [S1]

## 🛠️ 적용 사례 (Applied in summary)
현재 발견된 실제 적용 사례가 없습니다 — HTML용 Table 클래스와 가구용 Table 클래스를 네임스페이스로 분리하는 것이 이름 충돌 방지의 대표 사례다. [S1]

## 💻 코드 패턴 (Code patterns)
Namespace must be the first statement in the file (PHP):
```php
<?php
namespace Html; // must be the very first line
class Table {
    public $title = "";
    public $rows = 0;
}
```

## ✅ 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 Static Properties]], [[PHP Iterables]]
- **참조 맥락:** 이름 충돌 방지를 위한 그룹화 — 이터러블(Iterables) 챕터로 이어짐.

## 📚 출처 (Sources)
- [S1] W3Schools — PHP Namespaces — https://www.w3schools.com/php/php_namespaces.asp

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