58 lines
1.9 KiB
Python
58 lines
1.9 KiB
Python
# strategy_best2.py
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# Strategy pattern -- function-based implementation
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# selecting best promotion from current module globals
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"""
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>>> from decimal import Decimal
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>>> from strategy import Customer, LineItem, Order
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>>> joe = Customer('John Doe', 0)
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>>> ann = Customer('Ann Smith', 1100)
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>>> cart = [LineItem('banana', 4, Decimal('.5')),
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... LineItem('apple', 10, Decimal('1.5')),
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... LineItem('watermelon', 5, Decimal(5))]
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>>> Order(joe, cart, fidelity_promo)
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<Order total: 42.00 due: 42.00>
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>>> Order(ann, cart, fidelity_promo)
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<Order total: 42.00 due: 39.90>
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>>> banana_cart = [LineItem('banana', 30, Decimal('.5')),
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... LineItem('apple', 10, Decimal('1.5'))]
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>>> Order(joe, banana_cart, bulk_item_promo)
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<Order total: 30.00 due: 28.50>
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>>> long_cart = [LineItem(str(item_code), 1, Decimal(1))
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... for item_code in range(10)]
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>>> Order(joe, long_cart, large_order_promo)
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<Order total: 10.00 due: 9.30>
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>>> Order(joe, cart, large_order_promo)
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<Order total: 42.00 due: 42.00>
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# tag::STRATEGY_BEST_TESTS[]
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>>> Order(joe, long_cart, best_promo)
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<Order total: 10.00 due: 9.30>
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>>> Order(joe, banana_cart, best_promo)
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<Order total: 30.00 due: 28.50>
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>>> Order(ann, cart, best_promo)
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<Order total: 42.00 due: 39.90>
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# end::STRATEGY_BEST_TESTS[]
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"""
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# tag::STRATEGY_BEST2[]
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from decimal import Decimal
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from strategy import Order
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from strategy import (
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fidelity_promo, bulk_item_promo, large_order_promo # <1>
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)
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promos = [promo for name, promo in globals().items() # <2>
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if name.endswith('_promo') and # <3>
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name != 'best_promo' # <4>
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]
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def best_promo(order: Order) -> Decimal: # <5>
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"""Compute the best discount available"""
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return max(promo(order) for promo in promos)
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# end::STRATEGY_BEST2[]
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