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Design patterns

Overview​

Design patterns are reusable solutions to recurring problems in object-oriented and modular design (creational, structural, behavioral). They improve communication among developers but are not silver bullets—apply when the forces of your problem match the pattern’s intent.

Key concepts​

  • GoF patterns — Classic catalog from Gang of Four (Gamma et al.).
  • Idioms vs patterns — Language-specific habits vs broader structures.
  • Anti-patterns — “Silver bullet” misuse (e.g. God object, spaghetti code).
  • Functional alternatives — Many patterns map to functions, immutability, and composition.
  • Testability — Dependency injection often replaces singleton abuse.

Pattern selection (simplified)​

Sample: Strategy in TypeScript (sketch)​

type ShippingFn = (weightKg: number) => number;

const ground: ShippingFn = (w) => 5 + 1.2 * w;
const express: ShippingFn = (w) => 18 + 3.5 * w;

function quote(method: ShippingFn, weightKg: number) {
  return method(weightKg);
}

References​