2nd/10_Wiki/Topic_Programming/Programming & Language/코드 포매팅 (Code formatting).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-코드-포매팅-code-formatting	코드 포매팅 (Code Formatting)	10_Wiki/Topics	verified	self	Code Formatting Auto-formatting Prettier Black gofmt	none	A	0.9	applied	tooling style formatter prettier ruff black		2026-05-10	pending	language framework polyglot prettier-ruff-gofmt

코드 포매팅 (Code Formatting)

매 한 줄

"매 style debate 의 종결자". Code formatting 은 코드의 visual structure (whitespace, indent, line breaks, quote style) 를 deterministic rule 로 enforce 하는 tooling 영역. 2026 현재 매 모든 mainstream language 는 official 또는 de-facto formatter 를 가지며 (Black, Ruff format, Prettier, gofmt, rustfmt, dart format, ktlint), CI 의 commit hook 의 universal 으로 적용. 매 "어떻게 보일지" 의 human discussion 의 X — 매 tool 의 결정.

매 핵심

매 formatter 의 철학

• Opinionated (매 ideal): 매 minimal config — Black, gofmt, Prettier. 매 bikeshedding 의 elimination.
• Configurable (매 legacy): 매 ESLint stylistic rules, autopep8 — 매 team config drift 의 risk.
• Idempotent: format(format(x)) == format(x). 매 essential property — CI loop safety.
• AST-based: 매 token stream 의 parse → reformat. 매 regex 의 X.

매 linter vs formatter

• Formatter: whitespace, line breaks, quotes (style only). 매 semantics 의 X-change.
• Linter: bugs, anti-patterns, unused vars (semantics). 매 ESLint, Ruff check, golangci-lint.
• 2026 trend: Ruff (Python) 의 both 의 unify — ruff format + ruff check 의 매 single binary. Biome (JS/TS) 의 same path.

매 응용

1. Pre-commit hook: pre-commit (Python), lefthook, husky 의 매 staged file 의 format.
2. CI gate: ruff format --check / prettier --check — diff 가 있으면 fail.
3. Editor on-save: VS Code editor.formatOnSave: true + defaultFormatter.
4. Mass migration: git ls-files | xargs ruff format — 매 single PR 의 entire repo reformat.

💻 패턴

Prettier (JS/TS/JSON/MD/CSS) — 2026 v3

// .prettierrc.json
{
  "semi": false,
  "singleQuote": true,
  "trailingComma": "all",
  "printWidth": 100,
  "tabWidth": 2,
  "plugins": ["prettier-plugin-tailwindcss"]
}

# format all files in repo
npx prettier --write .
# CI check
npx prettier --check .

Ruff format (Python) — 2026 default Python formatter

# pyproject.toml
[tool.ruff]
line-length = 100
target-version = "py312"

[tool.ruff.format]
quote-style = "double"
indent-style = "space"
docstring-code-format = true  # format code in docstrings

ruff format .         # write
ruff format --check . # CI
ruff check --fix .    # lint + autofix

Black (Python, legacy but stable)

[tool.black]
line-length = 100
target-version = ["py312"]
skip-string-normalization = false

gofmt / goimports (Go) — bundled with toolchain

gofmt -w ./...
goimports -w ./...   # also organizes imports

// before
package main
import("fmt"
 "os")
func main(){fmt.Println(os.Args)}

// after gofmt
package main

import (
	"fmt"
	"os"
)

func main() {
	fmt.Println(os.Args)
}

rustfmt (Rust)

# rustfmt.toml
edition = "2024"
max_width = 100
imports_granularity = "Crate"
group_imports = "StdExternalCrate"

cargo fmt
cargo fmt -- --check  # CI

EditorConfig (cross-tool baseline)

# .editorconfig — every editor respects this
root = true

[*]
charset = utf-8
end_of_line = lf
insert_final_newline = true
trim_trailing_whitespace = true
indent_style = space

[*.{js,ts,tsx,json}]
indent_size = 2

[*.py]
indent_size = 4

[Makefile]
indent_style = tab

Pre-commit hook (universal)

# .pre-commit-config.yaml
repos:
  - repo: https://github.com/astral-sh/ruff-pre-commit
    rev: v0.6.0
    hooks:
      - id: ruff-format
      - id: ruff
        args: [--fix]
  - repo: https://github.com/pre-commit/mirrors-prettier
    rev: v4.0.0
    hooks:
      - id: prettier
        types_or: [javascript, typescript, json, markdown]

CI gate (GitHub Actions)

- name: Check formatting
  run: |
    ruff format --check .
    ruff check .
    npx prettier --check .

Mass-format ignore (avoid blame churn)

# .git-blame-ignore-revs
# Ruff format mass-apply 2026-04-15
abc123def456...

git config blame.ignoreRevsFile .git-blame-ignore-revs

매 결정 기준

상황	Approach
Python 신규 프로젝트	Ruff format (Black-compatible, 100x faster)
Python legacy	Black 유지 — Ruff 의 drop-in 의 가능
JS/TS	Prettier 또는 Biome (faster, Rust-based)
Go	gofmt (no choice, no config)
Rust	rustfmt
매 polyglot monorepo	dprint 또는 Trunk
Team debate 중	Opinionated formatter 의 즉시 채택 — 매 discussion close

기본값: Ruff (Python), Prettier 또는 Biome (web), gofmt (Go), rustfmt (Rust). 매 pre-commit + CI check.

🔗 Graph

• 부모: Code Quality · Developer Experience
• 변형: Linter · Static Analysis
• 응용: 153_pre-commit과_품질_게이트
• Adjacent: Prettier

🤖 LLM 활용

언제: Generated code 의 file write 후 항상 ruff format / prettier --write 의 run — LLM output 의 indent inconsistency 의 normalize. PR diff 의 minimize. 언제 X: Format-only PR 의 logic change 와 mix 의 X — separate commit / PR 로 분리. Reviewer 의 noise 의 reduction.

❌ 안티패턴

• Custom rules everywhere: 매 team-specific style 의 invention. 매 onboarding cost 의 increase. 매 Black/Prettier default 의 accept.
• Format on commit only: Editor save 의 X-format 의 경우 매 every commit 의 noise. Editor integration 의 essential.
• Format + logic 의 mixed PR: Review impossible. 매 separate PR.
• No CI check: Pre-commit 의 bypass 의 가능 (-n). 매 CI 의 source of truth.
• tabWidth debate: 매 EditorConfig 의 fix — once and forget.

🧪 검증 / 중복

• Verified (Prettier docs 2026, Ruff docs 0.6+, Go style guide).
• 신뢰도 A.

🕓 Changelog

날짜	변경
2026-05-08	Phase 1
2026-05-10	Manual cleanup — formatters (Ruff, Prettier, gofmt, rustfmt) + CI/pre-commit patterns