Generics

🎯 Mục tiêu: Type-safe code với generics.

---

💡 Generic Class

class Box<T> {
  T value;
  Box(this.value);
}

var intBox = Box<int>(42);
var stringBox = Box<String>("Hello");

---

📝 Generic Function

T first<T>(List<T> items) => items.first;

var number = first<int>([1, 2, 3]);  // Type inference
var word = first(['a', 'b', 'c']);

---

🔧 Constraints

class SortedList<T extends Comparable<T>> {
  final List<T> _items = [];

  void add(T item) {
    _items.add(item);
    _items.sort();
  }
}

---

✅ Checklist

• <T> cho type parameter
• extends cho constraints
• Collections là generic: List<T>, Map<K, V>

---