added chapter map to README
This commit is contained in:
Luciano Ramalho
4
07-dp-1class-func/README.rst
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4
07-dp-1class-func/README.rst
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Sample code for Chapter 6 - "Design patterns with first class functions"
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From the book "Fluent Python" by Luciano Ramalho (O'Reilly, 2015)
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http://shop.oreilly.com/product/0636920032519.do
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106
07-dp-1class-func/classic_strategy.py
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106
07-dp-1class-func/classic_strategy.py
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# classic_strategy.py
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# Strategy pattern -- classic implementation
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"""
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# BEGIN CLASSIC_STRATEGY_TESTS
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>>> joe = Customer('John Doe', 0) # <1>
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>>> ann = Customer('Ann Smith', 1100)
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>>> cart = [LineItem('banana', 4, .5), # <2>
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... LineItem('apple', 10, 1.5),
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... LineItem('watermellon', 5, 5.0)]
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>>> Order(joe, cart, FidelityPromo()) # <3>
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<Order total: 42.00 due: 42.00>
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>>> Order(ann, cart, FidelityPromo()) # <4>
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<Order total: 42.00 due: 39.90>
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>>> banana_cart = [LineItem('banana', 30, .5), # <5>
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... LineItem('apple', 10, 1.5)]
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>>> Order(joe, banana_cart, BulkItemPromo()) # <6>
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<Order total: 30.00 due: 28.50>
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>>> long_order = [LineItem(str(item_code), 1, 1.0) # <7>
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... for item_code in range(10)]
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>>> Order(joe, long_order, LargeOrderPromo()) # <8>
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<Order total: 10.00 due: 9.30>
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>>> Order(joe, cart, LargeOrderPromo())
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<Order total: 42.00 due: 42.00>
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# END CLASSIC_STRATEGY_TESTS
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"""
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# BEGIN CLASSIC_STRATEGY
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from abc import ABC, abstractmethod
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from collections import namedtuple
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Customer = namedtuple('Customer', 'name fidelity')
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class LineItem:
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def __init__(self, product, quantity, price):
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self.product = product
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self.quantity = quantity
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self.price = price
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def total(self):
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return self.price * self.quantity
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class Order: # the Context
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def __init__(self, customer, cart, promotion=None):
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self.customer = customer
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self.cart = list(cart)
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self.promotion = promotion
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def total(self):
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if not hasattr(self, '__total'):
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self.__total = sum(item.total() for item in self.cart)
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return self.__total
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def due(self):
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if self.promotion is None:
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discount = 0
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else:
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discount = self.promotion.discount(self)
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return self.total() - discount
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def __repr__(self):
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fmt = '<Order total: {:.2f} due: {:.2f}>'
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return fmt.format(self.total(), self.due())
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class Promotion(ABC): # the Strategy: an Abstract Base Class
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@abstractmethod
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def discount(self, order):
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"""Return discount as a positive dollar amount"""
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class FidelityPromo(Promotion): # first Concrete Strategy
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"""5% discount for customers with 1000 or more fidelity points"""
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def discount(self, order):
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return order.total() * .05 if order.customer.fidelity >= 1000 else 0
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class BulkItemPromo(Promotion): # second Concrete Strategy
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"""10% discount for each LineItem with 20 or more units"""
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def discount(self, order):
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discount = 0
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for item in order.cart:
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if item.quantity >= 20:
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discount += item.total() * .1
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return discount
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class LargeOrderPromo(Promotion): # third Concrete Strategy
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"""7% discount for orders with 10 or more distinct items"""
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def discount(self, order):
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distinct_items = {item.product for item in order.cart}
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if len(distinct_items) >= 10:
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return order.total() * .07
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return 0
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# END CLASSIC_STRATEGY
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20
07-dp-1class-func/promotions.py
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20
07-dp-1class-func/promotions.py
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def fidelity_promo(order):
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"""5% discount for customers with 1000 or more fidelity points"""
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return order.total() * .05 if order.customer.fidelity >= 1000 else 0
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def bulk_item_promo(order):
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"""10% discount for each LineItem with 20 or more units"""
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discount = 0
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for item in order.cart:
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if item.quantity >= 20:
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discount += item.total() * .1
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return discount
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def large_order_promo(order):
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"""7% discount for orders with 10 or more distinct items"""
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distinct_items = {item.product for item in order.cart}
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if len(distinct_items) >= 10:
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return order.total() * .07
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return 0
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93
07-dp-1class-func/strategy.py
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93
07-dp-1class-func/strategy.py
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# strategy.py
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# Strategy pattern -- function-based implementation
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"""
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# BEGIN STRATEGY_TESTS
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>>> joe = Customer('John Doe', 0) # <1>
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>>> ann = Customer('Ann Smith', 1100)
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>>> cart = [LineItem('banana', 4, .5),
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... LineItem('apple', 10, 1.5),
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... LineItem('watermellon', 5, 5.0)]
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>>> Order(joe, cart, fidelity_promo) # <2>
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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, .5),
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... LineItem('apple', 10, 1.5)]
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>>> Order(joe, banana_cart, bulk_item_promo) # <3>
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<Order total: 30.00 due: 28.50>
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>>> long_order = [LineItem(str(item_code), 1, 1.0)
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... for item_code in range(10)]
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>>> Order(joe, long_order, 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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# END STRATEGY_TESTS
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"""
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# BEGIN STRATEGY
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from collections import namedtuple
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Customer = namedtuple('Customer', 'name fidelity')
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class LineItem:
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def __init__(self, product, quantity, price):
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self.product = product
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self.quantity = quantity
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self.price = price
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def total(self):
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return self.price * self.quantity
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class Order: # the Context
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def __init__(self, customer, cart, promotion=None):
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self.customer = customer
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self.cart = list(cart)
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self.promotion = promotion
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def total(self):
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if not hasattr(self, '__total'):
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self.__total = sum(item.total() for item in self.cart)
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return self.__total
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def due(self):
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if self.promotion is None:
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discount = 0
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else:
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discount = self.promotion(self) # <1>
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return self.total() - discount
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def __repr__(self):
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fmt = '<Order total: {:.2f} due: {:.2f}>'
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return fmt.format(self.total(), self.due())
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# <2>
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def fidelity_promo(order): # <3>
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"""5% discount for customers with 1000 or more fidelity points"""
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return order.total() * .05 if order.customer.fidelity >= 1000 else 0
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def bulk_item_promo(order):
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"""10% discount for each LineItem with 20 or more units"""
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discount = 0
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for item in order.cart:
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if item.quantity >= 20:
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discount += item.total() * .1
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return discount
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def large_order_promo(order):
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"""7% discount for orders with 10 or more distinct items"""
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distinct_items = {item.product for item in order.cart}
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if len(distinct_items) >= 10:
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return order.total() * .07
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return 0
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# END STRATEGY
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108
07-dp-1class-func/strategy_best.py
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108
07-dp-1class-func/strategy_best.py
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# strategy_best.py
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# Strategy pattern -- function-based implementation
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# selecting best promotion from static list of functions
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"""
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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, .5),
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... LineItem('apple', 10, 1.5),
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... LineItem('watermellon', 5, 5.0)]
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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, .5),
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... LineItem('apple', 10, 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_order = [LineItem(str(item_code), 1, 1.0)
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... for item_code in range(10)]
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>>> Order(joe, long_order, 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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# BEGIN STRATEGY_BEST_TESTS
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>>> Order(joe, long_order, best_promo) # <1>
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<Order total: 10.00 due: 9.30>
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>>> Order(joe, banana_cart, best_promo) # <2>
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<Order total: 30.00 due: 28.50>
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>>> Order(ann, cart, best_promo) # <3>
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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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from collections import namedtuple
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Customer = namedtuple('Customer', 'name fidelity')
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class LineItem:
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def __init__(self, product, quantity, price):
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self.product = product
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self.quantity = quantity
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self.price = price
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def total(self):
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return self.price * self.quantity
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class Order: # the Context
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def __init__(self, customer, cart, promotion=None):
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self.customer = customer
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self.cart = list(cart)
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self.promotion = promotion
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def total(self):
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if not hasattr(self, '__total'):
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self.__total = sum(item.total() for item in self.cart)
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return self.__total
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def due(self):
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if self.promotion is None:
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discount = 0
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else:
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discount = self.promotion(self)
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return self.total() - discount
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def __repr__(self):
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fmt = '<Order total: {:.2f} due: {:.2f}>'
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return fmt.format(self.total(), self.due())
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def fidelity_promo(order):
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"""5% discount for customers with 1000 or more fidelity points"""
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return order.total() * .05 if order.customer.fidelity >= 1000 else 0
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def bulk_item_promo(order):
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"""10% discount for each LineItem with 20 or more units"""
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discount = 0
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for item in order.cart:
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if item.quantity >= 20:
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discount += item.total() * .1
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return discount
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def large_order_promo(order):
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"""7% discount for orders with 10 or more distinct items"""
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distinct_items = {item.product for item in order.cart}
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if len(distinct_items) >= 10:
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return order.total() * .07
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return 0
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# BEGIN STRATEGY_BEST
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promos = [fidelity_promo, bulk_item_promo, large_order_promo] # <1>
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def best_promo(order): # <2>
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"""Select best discount available
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"""
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return max(promo(order) for promo in promos) # <3>
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# END STRATEGY_BEST
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110
07-dp-1class-func/strategy_best2.py
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110
07-dp-1class-func/strategy_best2.py
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# 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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>>> joe = Customer('John Doe', 0)
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>>> ann = Customer('Ann Smith', 1100)
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>>> cart = [LineItem('banana', 4, .5),
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... LineItem('apple', 10, 1.5),
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... LineItem('watermellon', 5, 5.0)]
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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, .5),
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... LineItem('apple', 10, 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_order = [LineItem(str(item_code), 1, 1.0)
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... for item_code in range(10)]
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>>> Order(joe, long_order, 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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# BEGIN STRATEGY_BEST_TESTS
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>>> Order(joe, long_order, 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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from collections import namedtuple
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Customer = namedtuple('Customer', 'name fidelity')
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class LineItem:
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def __init__(self, product, quantity, price):
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self.product = product
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self.quantity = quantity
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self.price = price
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def total(self):
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return self.price * self.quantity
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class Order: # the Context
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def __init__(self, customer, cart, promotion=None):
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self.customer = customer
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self.cart = list(cart)
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self.promotion = promotion
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def total(self):
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if not hasattr(self, '__total'):
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self.__total = sum(item.total() for item in self.cart)
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return self.__total
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def due(self):
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if self.promotion is None:
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discount = 0
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else:
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discount = self.promotion(self)
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return self.total() - discount
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def __repr__(self):
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fmt = '<Order total: {:.2f} due: {:.2f}>'
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return fmt.format(self.total(), self.due())
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def fidelity_promo(order):
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"""5% discount for customers with 1000 or more fidelity points"""
|
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return order.total() * .05 if order.customer.fidelity >= 1000 else 0
|
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|
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|
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def bulk_item_promo(order):
|
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"""10% discount for each LineItem with 20 or more units"""
|
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discount = 0
|
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for item in order.cart:
|
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if item.quantity >= 20:
|
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discount += item.total() * .1
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return discount
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|
||||
|
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def large_order_promo(order):
|
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"""7% discount for orders with 10 or more distinct items"""
|
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distinct_items = {item.product for item in order.cart}
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if len(distinct_items) >= 10:
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return order.total() * .07
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return 0
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# BEGIN STRATEGY_BEST2
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promos = [globals()[name] for name in globals() # <1>
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if name.endswith('_promo') # <2>
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and name != 'best_promo'] # <3>
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def best_promo(order):
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"""Select best discount available
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"""
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return max(promo(order) for promo in promos) # <4>
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# END STRATEGY_BEST2
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93
07-dp-1class-func/strategy_best3.py
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93
07-dp-1class-func/strategy_best3.py
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@@ -0,0 +1,93 @@
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# strategy_best3.py
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# Strategy pattern -- function-based implementation
|
||||
# selecting best promotion from imported module
|
||||
|
||||
"""
|
||||
>>> from promotions import *
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>>> joe = Customer('John Doe', 0)
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||||
>>> ann = Customer('Ann Smith', 1100)
|
||||
>>> cart = [LineItem('banana', 4, .5),
|
||||
... LineItem('apple', 10, 1.5),
|
||||
... LineItem('watermellon', 5, 5.0)]
|
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>>> Order(joe, cart, fidelity_promo)
|
||||
<Order total: 42.00 due: 42.00>
|
||||
>>> Order(ann, cart, fidelity_promo)
|
||||
<Order total: 42.00 due: 39.90>
|
||||
>>> banana_cart = [LineItem('banana', 30, .5),
|
||||
... LineItem('apple', 10, 1.5)]
|
||||
>>> Order(joe, banana_cart, bulk_item_promo)
|
||||
<Order total: 30.00 due: 28.50>
|
||||
>>> long_order = [LineItem(str(item_code), 1, 1.0)
|
||||
... for item_code in range(10)]
|
||||
>>> Order(joe, long_order, large_order_promo)
|
||||
<Order total: 10.00 due: 9.30>
|
||||
>>> Order(joe, cart, large_order_promo)
|
||||
<Order total: 42.00 due: 42.00>
|
||||
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||||
# BEGIN STRATEGY_BEST_TESTS
|
||||
|
||||
>>> Order(joe, long_order, best_promo)
|
||||
<Order total: 10.00 due: 9.30>
|
||||
>>> Order(joe, banana_cart, best_promo)
|
||||
<Order total: 30.00 due: 28.50>
|
||||
>>> Order(ann, cart, best_promo)
|
||||
<Order total: 42.00 due: 39.90>
|
||||
|
||||
# END STRATEGY_BEST_TESTS
|
||||
"""
|
||||
|
||||
from collections import namedtuple
|
||||
import inspect
|
||||
|
||||
import promotions
|
||||
|
||||
Customer = namedtuple('Customer', 'name fidelity')
|
||||
|
||||
|
||||
class LineItem:
|
||||
|
||||
def __init__(self, product, quantity, price):
|
||||
self.product = product
|
||||
self.quantity = quantity
|
||||
self.price = price
|
||||
|
||||
def total(self):
|
||||
return self.price * self.quantity
|
||||
|
||||
|
||||
class Order: # the Context
|
||||
|
||||
def __init__(self, customer, cart, promotion=None):
|
||||
self.customer = customer
|
||||
self.cart = list(cart)
|
||||
self.promotion = promotion
|
||||
|
||||
def total(self):
|
||||
if not hasattr(self, '__total'):
|
||||
self.__total = sum(item.total() for item in self.cart)
|
||||
return self.__total
|
||||
|
||||
def due(self):
|
||||
if self.promotion is None:
|
||||
discount = 0
|
||||
else:
|
||||
discount = self.promotion(self)
|
||||
return self.total() - discount
|
||||
|
||||
def __repr__(self):
|
||||
fmt = '<Order total: {:.2f} due: {:.2f}>'
|
||||
return fmt.format(self.total(), self.due())
|
||||
|
||||
# BEGIN STRATEGY_BEST3
|
||||
|
||||
promos = [func for name, func in
|
||||
inspect.getmembers(promotions, inspect.isfunction)]
|
||||
|
||||
def best_promo(order):
|
||||
"""Select best discount available
|
||||
"""
|
||||
return max(promo(order) for promo in promos)
|
||||
|
||||
# END STRATEGY_BEST3
|
||||
|
||||
|
||||
Reference in New Issue
Block a user