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practice/prep11.py

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+"""CSC110 Fall 2021 Prep 11: Programming Exercises
+
+Instructions (READ THIS FIRST!)
+===============================
+
+This Python module contains the data class definitions that serve as the foundation
+for our computational model of a food delivery system, as we discussed in this week's
+prep reading.
+
+Please read through this file carefully, and follow all instructions described below.
+We have marked each place you need to write code with the word "TODO".
+As you complete your work in this file, delete each TODO comment.
+
+
+Copyright and Usage Information
+===============================
+
+This file is provided solely for the personal and private use of students
+taking CSC110 at the University of Toronto St. George campus. All forms of
+distribution of this code, whether as given or with any changes, are
+expressly prohibited. For more information on copyright for CSC110 materials,
+please consult our Course Syllabus.
+
+This file is Copyright (c) 2021 David Liu, Mario Badr, and Tom Fairgrieve.
+"""
+from __future__ import annotations
+
+from dataclasses import dataclass
+import datetime
+from typing import Optional
+
+
+@dataclass
+class Restaurant:
+    """A place that serves food.
+
+    Attributes:
+      - name: the name of the restaurant
+      - address: the address of the restaurant
+      - menu: the menu of the restaurant with the name of the dish mapping to
+        the price
+      - location: the location of the restaurant as (latitude, longitude)
+
+    Representation Invariants:
+      - self.name != ''
+      - self.address != ''
+      - all(self.menu[item] >= 0 for item in self.menu)
+      - -90 <= self.location[0] <= 90
+      - -180 <= self.location[1] <= 180
+
+    Sample Usage:
+    >>> mcdonalds = Restaurant(name='McDonalds', address='160 Spadina Ave',\
+                               menu={'fries': 4.5}, location=(43.649, -79.397))
+    """
+    name: str
+    address: str
+    menu: dict[str, float]
+    location: tuple[float, float]
+
+
+@dataclass
+class Customer:
+    """A person who orders food.
+
+    Instance Attributes:
+      - name: Customer's name
+      - location: Customer's position in (latitutde, longitude) format.
+
+    Representation Invariants:
+      - self.name != ''
+      - -90 <= self.location[0] <= 90
+      - -180 <= self.location[1] <= 180
+
+    Sample Usage:
+    >>> david = Customer('David', (44.649, -79.115))
+    """
+    name: str
+    location: tuple[float, float]
+
+
+@dataclass
+class Order:
+    """A food order from a customer.
+
+    Attributes:
+      - customer: the customer who placed this order
+      - restaurant: the restaurant the order is placed for
+      - food_items: a mapping from names of food to the quantity being ordered
+      - start_time: the time the order was placed
+      - courier: the courier assigned to this order (initially None)
+      - end_time: the time the order was completed by the courier (initially None)
+
+    Representation Invariants:
+      - self.food_items != {}
+      - all(self.food_items[item] > 0 for item in self.food_items)
+      - all(f in self.restaurant.menu for f in self.food_items)
+
+    Sample Usage:
+    >>> david = Customer('David', (44.649, -79.115))
+    >>> mcdonalds = Restaurant(name='McDonalds', address='160 Spadina Ave',\
+                               menu={'fries': 4.5}, location=(43.649, -79.397))
+    >>> order = Order(customer=david, restaurant=mcdonalds,\
+                      food_items={'fries': 10},\
+                      start_time=datetime.datetime(2020, 11, 5, 11, 30))
+    >>> order.courier is None  # Illustrating default values
+    True
+    >>> order.end_time is None
+    True
+    """
+    customer: Customer
+    restaurant: Restaurant
+    food_items: dict[str, int]
+    start_time: datetime.datetime
+    courier: Optional[Courier] = None
+    end_time: Optional[datetime.datetime] = None
+
+
+@dataclass
+class Courier:
+    """A person who delivers food orders from restaurants to customers.
+
+    Deliberately left blank (you don't need to do anything here).
+    We'll discuss this data class in lecture!
+    """
+
+
+def total_cost(order: Order) -> float:
+    """Return the total cost of the food items in this order.
+
+    Done: add one doctest example for this function that:
+          1. Creates a valid customer and restaurant, where the restaurant
+             has at least two different foods on the menu.
+          2. Creates an order for this customer and restaurant that orders
+             >= 2 different food items, and >= 3 quantity of each item.
+          3. Calculates the total cost of the order.
+             (Use math.isclose to avoid rounding error with floats.)
+
+    >>> import math
+    >>> david = Customer('David', (44.649, -79.115))
+    >>> mcdonalds = Restaurant(name='McDonalds', address='160 Spadina Ave',\
+                               menu={'fries': 4.5, 'strawberries': 9999, 'ice cream': 1},\
+                               location=(43.649, -79.397))
+    >>> order = Order(customer=david, restaurant=mcdonalds,\
+                      food_items={'fries': 10, 'strawberries': 4},\
+                      start_time=datetime.datetime(2020, 11, 5, 11, 30))
+    >>> math.isclose(total_cost(order), 40041.0)
+    True
+    """
+    return sum([order.food_items[f] * order.restaurant.menu[f] for f in order.food_items])
+
+
+if __name__ == '__main__':
+    import python_ta
+    python_ta.check_all(config={
+        'max-line-length': 100,
+        'extra-imports': ['python_ta.contracts', 'dataclasses', 'datetime'],
+        'disable': ['R1705', 'C0200'],
+    })
+
+    import python_ta.contracts
+    python_ta.contracts.DEBUG_CONTRACTS = False
+    python_ta.contracts.check_all_contracts()
+
+    import doctest
+    doctest.testmod()