Dart - Override Operators

add-product-bag.dart

void main() {
  Bag bag = Bag(items: []);
  print('Total: ${bag.total}');
  
  Product p1 = Product(name: 'Pen', price: 1.15);
  print('Total: ${bag+p1}');
  
  Product p2 = Product(name: 'Pencil', price: 2);
  print('Total: ${bag+p2}');
}

class Bag {
  List<Product> items;
  double total;
  
  Bag({this.items, this.total = 0});
  
  double operator +(Product product) {
    items.add(product);
    
    total += product.price;
    return total;
  }
}

class Product {
  String name;
  double price;
  
  Product({this.name, this.price});
}