Latihan 1: State Pattern — Design Patterns

Latihan 1 dari materi State Pattern di Design Patterns — praktek dengan editor kode interaktif, test case otomatis, dan hint terpandu. Langsung jalan di browser.

Bangun vending machine dengan state pattern. createMachine(stock) return object dengan method:

insertCoin() — jika state "NoMoney" → pindah ke "HasMoney", return "coin accepted". Jika "HasMoney" → return "coin already inserted". Jika "SoldOut" → return "machine sold out".
selectProduct() — jika state "HasMoney" → kurangi stock. Jika stock 0 setelahnya → pindah "SoldOut", else "NoMoney". Return "dispensed". Jika state "NoMoney" → return "insert coin first". Jika "SoldOut" → return "machine sold out".
getState() — return nama state saat ini.

State awal: "NoMoney" jika stock > 0, "SoldOut" jika stock = 0.

Hint

State pattern: object punya currentState. Setiap action (insertCoin, selectProduct, dispense) bergantung state saat ini.
States: Idle (tunggu coin), HasCoin (tunggu selection), Dispensing (keluarkan produk), SoldOut (stok habis).
Transisi state: insertCoin di Idle → HasCoin. selectProduct di HasCoin → Dispensing atau SoldOut. Stok kosong → SoldOut permanen.