45 lines
1.3 KiB
Python
45 lines
1.3 KiB
Python
# strategy_best.py
|
|
# Strategy pattern -- function-based implementation
|
|
# selecting best promotion from static list of functions
|
|
|
|
"""
|
|
>>> from strategy import Customer, LineItem
|
|
>>> joe = Customer('John Doe', 0)
|
|
>>> ann = Customer('Ann Smith', 1100)
|
|
>>> cart = [LineItem('banana', 4, Decimal('.5')),
|
|
... LineItem('apple', 10, Decimal('1.5')),
|
|
... LineItem('watermelon', 5, Decimal(5))]
|
|
>>> banana_cart = [LineItem('banana', 30, Decimal('.5')),
|
|
... LineItem('apple', 10, Decimal('1.5'))]
|
|
>>> long_cart = [LineItem(str(item_code), 1, Decimal(1))
|
|
... for item_code in range(10)]
|
|
|
|
# tag::STRATEGY_BEST_TESTS[]
|
|
|
|
>>> Order(joe, long_cart, best_promo) # <1>
|
|
<Order total: 10.00 due: 9.30>
|
|
>>> Order(joe, banana_cart, best_promo) # <2>
|
|
<Order total: 30.00 due: 28.50>
|
|
>>> Order(ann, cart, best_promo) # <3>
|
|
<Order total: 42.00 due: 39.90>
|
|
|
|
# end::STRATEGY_BEST_TESTS[]
|
|
"""
|
|
|
|
from decimal import Decimal
|
|
|
|
from strategy import Order
|
|
from strategy import fidelity_promo, bulk_item_promo, large_order_promo
|
|
|
|
# tag::STRATEGY_BEST[]
|
|
|
|
promos = [fidelity_promo, bulk_item_promo, large_order_promo] # <1>
|
|
|
|
|
|
def best_promo(order: Order) -> Decimal: # <2>
|
|
"""Compute the best discount available"""
|
|
return max(promo(order) for promo in promos) # <3>
|
|
|
|
|
|
# end::STRATEGY_BEST[]
|