#designpattern #python #programming #apply #datastructure #combination
- The decorator is used to register each promo type into a list, so in that way we can select the best promo to apply for each person
Promotion = Callable[[Order], Decimal]
promos: list[Promotion] = []
def promotion(promo: Promotion) -> Promotion:
promos.append(promo)
return promo
def best_promo(order: Order) -> Decimal:
"""Compute the best discount available"""
return max(promo(order) for promo in promos)
@promotion
def fidelity(order: Order) -> Decimal:
"""5% discount for customers with 1000 or more fidelity points"""
if order.customer.fidelity >= 1000:
return order.total() * Decimal('0.05')
return Decimal(0)
@promotion
def bulk_item(order: Order) -> Decimal:
"""10% discount for each LineItem with 20 or more units"""
discount = Decimal(0)
for item in order.cart:
if item.quantity >= 20:
discount += item.total() * Decimal('0.1')
return discount
@promotion
def large_order(order: Order) -> Decimal:
"""7% discount for orders with 10 or more distinct items"""
distinct_items = {item.product for item in order.cart}
if len(distinct_items) >= 10:
return order.total() * Decimal('0.07')
return Decimal(0)