elegant-code（优雅的代码）

Elegant Code

Elegant code = Correctness + Clarity + Minimal complexity + Natural efficiency + Easy change.

Not "shortest" or "cleverest." The solution that makes readers think: *"Of course. That's simple, right, and hard to mess up."*

Optimization Priority (in order)

1. Correctness & safety — does what it claims, handles edge cases
2. Clarity of intent — reader answers "what/why/how" from code itself
3. Simplicity — minimal concepts that still solve the problem
4. Changeability — modifications are localized and low-risk
5. Efficiency — good algorithms; performance from good design, not micro-optimizations

Elegant vs "Smart" Code

The Workflow

Use this sequence when writing or refactoring:

1. Clarify the problem

• Define inputs, outputs, invariants, constraints, failure modes
• Identify postconditions (what must be true after)
• List edge cases and "gotchas"

2. Choose simplest correct approach

• Pick simplest algorithm/data structure meeting constraints
• Prefer fewer concepts over more layers
• If adding abstraction, state what complexity it removes

3. Design shape before details

• Outline modules/functions and responsibilities
• Decide boundaries: pure logic vs side effects (I/O, database, network)

4. Write readable-by-default code

• Clear names, small units, straightforward control flow
• Make "happy path" obvious; handle errors intentionally

5. Add guardrails

• Validation, assertions (where appropriate), tests
• Define invalid input handling

6. Refine (remove, simplify, clarify)

• Remove duplication, tighten interfaces, reduce nesting
• Each unit should read like a single thought

7. Verify against reality

• Run tests; benchmark if performance matters
• Confirm behavior matches original problem statement

Core Rules

Rule 1 — Preserve intent above everything

Reader must answer: What does this do? Why? What constraints? What can go wrong?

• Comments explain why, tradeoffs, constraints—not what code does
• If you need comments to explain *what*, the code is unclear

Rule 2 — Minimize concepts, not lines

Keep distinct "ideas" (types, abstractions, layers, config knobs) minimal.

• Prefer one good function over a mini-framework
• No "future-proofing" without concrete known need
• If abstraction adds indirection without removing complexity, remove it

Rule 3 — Common case simple; edge cases explicit

• Happy path easy to follow
• Edge cases via early returns, guard clauses, explicit validation
• Avoid deep nesting hiding the main story

Rule 4 — Small, cohesive units

• One primary responsibility per function/module/class
• Group related logic; separate unrelated concerns
• If name needs "and" (parseAndSave), it's doing too much

Rule 5 — Explicit data flow over hidden state

• Data through parameters and return values, not globals/singletons/mutable shared state
• If you can't test without elaborate setup, hidden context exists
• If call order matters, make it explicit

Rule 6 — DRY knowledge, not syntax

• Unify if two places must change together
• Allow small obvious repetition if abstraction is harder to read
• Duplicate code sometimes cheaper than leaky abstraction

Rule 7 — Right algorithmic shape

• Choose algorithms/data structures appropriate to constraints
• Prefer clarity unless profiling demands complexity
• Prefer asymptotic wins over micro-optimizations

Rule 8 — Make invalid states unrepresentable

• Represent domain constraints in types/structures so illegal combinations are impossible
• Validate at boundaries, convert to trusted internal representations

Rule 9 — Local reasoning

• Understand a unit without chasing definitions across codebase
• Small interfaces, directness over indirection
• Configuration close to usage or centralized with clear naming

Rule 10 — Idiomatic but readable

• Follow language/project conventions
• Don't use obscure tricks only experts recognize
• If idiom is compact but unclear, choose clearer form

Micro-Rules

Naming

• DO: Names encode intent and domain meaning, not mechanics
• DO: Concrete nouns/verbs: calculate_total, is_valid, parse_header
• AVOID: Vague names: data, process, handle, doThing, tmp, manager
• DO: One concept → one term (consistent vocabulary)

Functions

• Short enough for working memory
• Inputs/outputs obvious and stable
• Side effects clear from name or context
• Favor pure functions for core logic
• I/O at edges ("functional core, imperative shell")

Control Flow

• Avoid deep nesting; use guard clauses
• Early exits for invalid conditions
• Straightforward over clever

Error Handling

• Decide: recover, retry, fallback, or fail fast—then implement consistently
• Errors carry enough context to debug
• Validate at boundaries
• Never swallow errors silently

Dependencies

• Depend on stable interfaces, not unstable internals
• Minimal and purposeful dependencies
• Inject dependencies where it improves testability

Self-Review Checklist

Before finalizing code, verify:

• Correctness: Meets requirements; edge cases handled; failures intentional
• Clarity: Names meaningful; reads top-to-bottom; minimal mental jumps
• Simplicity: No unnecessary abstractions; minimal moving parts
• Cohesion: Each unit has one job; responsibilities not mixed
• Coupling: Dependencies minimal; interfaces small and stable
• Data flow: Inputs/outputs explicit; minimal hidden state
• Error handling: Consistent strategy; errors include context
• Efficiency: Algorithm/data structures fit constraints; no obvious waste
• Consistency: Patterns match codebase norms
• Testability: Core logic testable easily; tests exist for tricky parts

Refactor Decision Rules

Refactor if:

• Function/module cannot be summarized in one sentence
• Must read twice to trust it
• One change requires edits in many unrelated places
• Bugs cluster in same area repeatedly
• Keep adding special cases ("just one more flag")

Avoid refactoring if:

• No tests and behavior unclear (add tests first)
• Code stable and rarely changed, improvements purely aesthetic
• Near deadline and risk is high (smallest safe improvements only)

Detailed References

• Measuring elegance: See references/scorecard.md for the elegance scorecard, objective metrics, and improvement checklist
• Anti-patterns: See references/anti-patterns.md for what kills elegance and "smart code" smells
• Continuous improvement: See references/continuous-improvement.md for the Continuous Elegance Loop and practices