python-patterns/3-tier.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

class Data(object):

    products = {
            'milk': { 'price': 1.50, 'quantity': 10 },
            'eggs': { 'price': 0.20, 'quantity': 100 },
            'cheese': { 'price': 2.00, 'quantity': 10 }
    }


class BusinessLogic(object):

    def __init__(self):
        self.data = Data()

    def product_list(self):
        return self.data.products.keys()

    def product_information(self, product):
        return self.data.products.get(product, None)


class Ui(object):

    def __init__(self):
        self.business_logic = BusinessLogic()

    def get_product_list(self):
        print('PRODUCT LIST:')
        for product in self.business_logic.product_list():
            print(product)
        print('')

    def get_product_information(self, product):
        product_info = self.business_logic.product_information(product)
        if product_info:
            print('PRODUCT INFORMATION:')
            print('Name: {0}, Price: {1:.2f}, Quantity: {2:}'.format(
                   product.title(), product_info.get('price', 0),
                   product_info.get('quantity', 0)))
        else:
            print('That product "{0}" does not exist in the records'.format(product))


def main():
    ui = Ui()
    ui.get_product_list()
    ui.get_product_information('cheese')
    ui.get_product_information('eggs')
    ui.get_product_information('milk')
    ui.get_product_information('arepas')

if __name__ == '__main__':
    main()