Table of Contents

• 🧩 Patterns
• Categories
  • Idiomatic Go patterns
  • Design patterns (Go flavor)
• Structure

🧩 Patterns

Idiomatic Go patterns and classic design patterns, each with a short explanation and a runnable demo. Promoted here from the journal once understood well enough to teach.

Categories

Idiomatic Go patterns

• Functional options (func(*Config))
• Constructor injection / "accept interfaces, return structs"
• Error wrapping & sentinel errors
• context propagation & cancellation
• Worker pool · fan-in/fan-out · pipeline · semaphore (bounded concurrency)
• errgroup for fan-out-with-errors
• Table-driven tests
• Graceful shutdown (signal.NotifyContext + Server.Shutdown)

Design patterns (Go flavor)

• Strategy (via interfaces / first-class funcs)
• Decorator / middleware (func(http.Handler) http.Handler)
• Factory · Singleton (sync.Once) · Adapter · Observer
• Repository · Ports & Adapters (hexagonal)

Structure

patterns/
├── functional-options/   main.go + README.md
├── worker-pool/          main.go + main_test.go + README.md
├── middleware/           …
└── …

Each folder: a README.md (what/when/why + trade-offs) and runnable code. Cross-link to the concurrency cheatsheet and the project that uses the pattern.

Pattern	Category	Used in
Worker pool	concurrency	crawler
Middleware	web	REST API
Ports & adapters	architecture	capstone

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⬅ README