Update code for class on March 10, 2020

Examples/enums.py

@@ -0,0 +1,23 @@
+from enum import Enum
+
+
+class Weekday(Enum):
+    MONDAY = 1
+    TUESDAY = 2
+    WEDNESDAY = 3
+    THURSDAY = 4
+    FRIDAY = 5
+    SATURDAY = 6
+    SUNDAY = 7
+
+
+weekdays = (Weekday.MONDAY, Weekday.TUESDAY, Weekday.WEDNESDAY, Weekday.THURSDAY, Weekday.FRIDAY)
+weekends = (Weekday.SATURDAY, Weekday.SUNDAY)
+
+weekday_wake_up = "7am"
+weekend_wake_up = "9am"
+
+for day in Weekday:
+    print(f'Today is {day.name.capitalize()}')
+    wake_time = weekday_wake_up if day in weekdays else weekend_wake_up
+    print(f'Wake up at {wake_time}\n')

Examples/example_10_inheritance.py

@@ -40,7 +40,8 @@ def __init__(self, length):
         super().__init__(length, length)
 
 
-shapes = [Square(10), Circle(20), Rectangle(3.4, 1.5)]
+if __name__ == '__main__':
+    shapes = [Square(10), Circle(20), Rectangle(3.4, 1.5)]
 
-for shape in shapes:
-    print(f'{shape} area is {shape.area()}')
+    for shape in shapes:
+        print(f'{shape} area is {shape.area()}')

Examples/example_11_args_kwargs.py

@@ -46,7 +46,8 @@ def __init__(self, length, *args, **kwargs):
         super().__init__(length, length, *args, **kwargs)
 
 
-shapes = [Square(10, x=0, y=0), Circle(20, -1, 1), Rectangle(3.4, 1.5, 20, y=5)]
+if __name__ == '__main__':
+    shapes = [Square(10, x=0, y=0), Circle(20, -1, 1), Rectangle(3.4, 1.5, 20, y=5)]
 
-for shape in shapes:
-    print(f'{shape} area is {shape.area()}')
+    for shape in shapes:
+        print(f'{shape} area is {shape.area()}')

Examples/example_12_inheritance_with_abc.py

@@ -0,0 +1,50 @@
+import abc  # Abstract Base Class
+from math import pi
+
+
+class Shape(abc.ABC):
+    @abc.abstractmethod
+    def area(self):
+        pass
+
+    @abc.abstractmethod
+    def circumference(self):
+        pass
+
+    def __str__(self):
+        return type(self).__name__
+
+
+class Circle(Shape):
+    def __init__(self, r):
+        self.r = r
+
+    def area(self):
+        return pi * self.r ** 2
+
+    def circumference(self):
+        return 2 * pi * self.r
+
+
+class Rectangle(Shape):
+    def __init__(self, length, width):
+        self.l = length
+        self.w = width
+
+    def area(self):
+        return self.l * self.w
+
+    def circumference(self):
+        return 2 * self.l + 2 * self.w
+
+
+class Square(Rectangle):
+    def __init__(self, length):
+        super().__init__(length, length)
+
+
+if __name__ == '__main__':
+    shapes = [Square(10), Circle(20), Rectangle(3.4, 1.5)]
+
+    for shape in shapes:
+        print(f'{shape} area is {shape.area()}')

Examples/example_1_bike_without_classes.py

@@ -1,50 +1,38 @@
-from datetime import datetime
+def update_sale_price(bike, sale_price):
+    if bike['sold'] is True:
+        raise Exception("Action not allowed. Bike has already been sold")
+    bike['sale_price'] = sale_price
 
 
-def lookup_msrp_value(make, model):
-    """
-    Determine original sale price of a bike when new
-    """
-    return 1000
-
-
-def set_sale_price(bike):
-    original_value = lookup_msrp_value(bike['make'], bike['model'])
-    current_year = datetime.now().year
-    current_value = original_value * (1 - (current_year - bike['year']) * 0.015)
-    current_value = current_value * bike['condition']
-    bike['sale_price'] = current_value
-
-
-def create_bike(cost, make, model, year, condition):
+def create_bike(description, cost, sale_price, condition):
     return {
+        'description': description,
         'cost': cost,
-        'make': make,
-        'model': model,
-        'year': year,
+        'sale_price': sale_price,
         'condition': condition,
         'sold': False,
     }
 
 
-def sell(bike):
+def sell(bike, sold_for=None):
+    if sold_for:
+        update_sale_price(bike, sold_for)
     bike['sold'] = True
     profit = bike['sale_price'] - bike['cost']
     return profit
 
 
-bike1 = create_bike(100, 'Univega', 'Alpina', 1999, 0.5)
+bike1 = create_bike('Univega Alpina, orange', cost=100, sale_price=500, condition=0.5)
 # bike1 = {
 #         'cost': 100,
-#         'make': 'Univega',
-#         'model': 'Alpina',
-#         'year': 1999,
 #         'condition': 0.5,
+#         'description': 'Univega Alpina, orange',
+#         'sale_price': 500,
 #         'sold': False,
 #     }
 
-set_sale_price(bike1)
+update_sale_price(bike1, 350)
 # bike1['sale_price'] = 350.00
 
-sell(bike1)
+print(sell(bike1))
 # bike1['sold'] = True

Examples/example_2_using_classes.py

@@ -1,11 +1,9 @@
 from Examples.example_5_methods import Bike, Condition
 
-bike = Bike(100, 'Univega', 'Alpina', 1999, Condition.OKAY)
+bike = Bike('Univega Alpina, orange', Condition.OKAY, sale_price=500, cost=100)
 
-bike.update_sale_price()          # sale price = $350
+bike.service(spent=30, sale_price=600)  # cost=$130, sale_price=$600
 
-bike.service(30, Condition.GOOD)  # cost = $130
+print(bike.sale_price)                  # 600
 
-print(bike.sale_price)            # sale price = $560
-
-bike.sell()                       # profit = $430
+print(bike.sell())                             # sold=True

Examples/example_4_attributes.py

@@ -1,14 +1,12 @@
 class Bike(object):
-    def __init__(self, cost, make, model, year, condition):
+    def __init__(self, description, condition, sale_price, cost=0):
         # Different initial values for every new instance
-        self.cost = cost
-        self.make = make
-        self.model = model
-        self.year = year
+        self.description = description
         self.condition = condition
+        self.sale_price = sale_price
+        self.cost = cost
 
-        # Same initial values for every new instance
-        self.sale_price = None
+        # Same initial value for every new instance
         self.sold = False
 
     def update_sale_price(self):
@@ -17,5 +15,5 @@ def update_sale_price(self):
     def sell(self):
         pass
 
-    def service(self, cost, new_condition):
+    def service(self):
         pass

Examples/example_5_methods.py

@@ -1,4 +1,3 @@
-from datetime import datetime
 from enum import Enum
 
 
@@ -9,27 +8,23 @@ class Condition(Enum):
     BAD = 0.2
 
 
+class MethodNotAllowed(Exception):
+    pass
+
+
 class Bike(object):
-    def __init__(self, cost, make, model, year, condition):
-        self.cost = cost
-        self.make = make
-        self.model = model
-        self.year = year
+    def __init__(self, description, condition, sale_price, cost=0):
+        self.description = description
         self.condition = condition
+        self.sale_price = sale_price
+        self.cost = cost
 
-        self.sale_price = self.update_sale_price()
         self.sold = False
 
-    def update_sale_price(self):
-        """
-        Set the current sale price based on the make, model, age, and condition
-        """
-        original_value = lookup_msrp_value(self.make, self.model)
-        current_year = datetime.now().year
-        current_value = original_value * (1 - (current_year - self.year) * 0.015)
-        current_value = current_value * self.condition.value
-        self.sale_price = current_value
-        return self.sale_price
+    def update_sale_price(self, sale_price):
+        if self.sold:
+            raise MethodNotAllowed('Bike has already been sold')
+        self.sale_price = sale_price
 
     def sell(self):
         """
@@ -39,18 +34,12 @@ def sell(self):
         profit = self.sale_price - self.cost
         return profit
 
-    def service(self, cost, new_condition):
+    def service(self, spent, sale_price=None, condition=None):
         """
-        Service the bike and update sale price
+        Service the bike and update attributes
         """
-        self.cost += cost
-        self.condition = new_condition
-        self.update_sale_price()
-        return self.sale_price
-
-
-def lookup_msrp_value(make, model):
-    """
-    Determine original sale price of a bike when new
-    """
-    return 1000
+        self.cost += spent
+        if sale_price:
+            self.update_sale_price(sale_price)
+        if self.condition:
+            self.condition = condition

Examples/example_6_dunder_methods.py

@@ -1,4 +1,3 @@
-from datetime import datetime
 from enum import Enum
 
 
@@ -10,32 +9,22 @@ class Condition(Enum):
 
 
 class Bike(object):
-
-    def __init__(self, cost, make, model, year, condition):
-        self.cost = cost
-        self.make = make
-        self.model = model
-        self.year = year
+    def __init__(self, description, condition, sale_price, cost=0):
+        self.description = description
         self.condition = condition
+        self.sale_price = sale_price
+        self.cost = cost
 
-        self.sale_price = self.update_sale_price()
         self.sold = False
-
         print(f'New bike: {self}')
 
     def __del__(self):
         print(f'Deleting bike: {self}')
 
-    def update_sale_price(self):
-        """
-        Set the current sale price based on the make, model, age, and condition
-        """
-        original_value = lookup_msrp_value(self.make, self.model)
-        current_year = datetime.now().year
-        current_value = original_value * (1 - (current_year - self.year) * 0.015)
-        current_value = current_value * self.condition.value
-        self.sale_price = current_value
-        return self.sale_price
+    def update_sale_price(self, sale_price):
+        if self.sold:
+            return Exception('Action not allowed. Bike has already been sold')
+        self.sale_price = sale_price
 
     def sell(self):
         """
@@ -45,36 +34,33 @@ def sell(self):
         profit = self.sale_price - self.cost
         return profit
 
-    def service(self, cost, new_condition):
+    def service(self, spent, sale_price=None, condition=None):
         """
-        Service the bike and update sale price
+        Service the bike and update attributes
         """
-        self.cost += cost
-        self.condition = new_condition
-        self.update_sale_price()
-        return self.sale_price
+        self.cost += spent
+        if sale_price:
+            self.update_sale_price(sale_price)
+        if self.condition:
+            self.condition = condition
 
     def __repr__(self):
-        return f'Bike: {self.year} {self.make} {self.model} ({"sold" if self.sold else self.sale_price})'
+        sold_or_price = "sold" if self.sold else f"${self.sale_price}"
+        return f'Bike: {self.description} ({sold_or_price})'
 
     def __str__(self):
-        return f'{self.year} {self.make} {self.model}'
-
-
-def lookup_msrp_value(make, model):
-    """
-    Determine original sale price of a bike when new
-    """
-    return 1000
+        return self.description
 
 
 if __name__ == '__main__':
-    bike = Bike(100, 'Univega', 'Alpina', 1999, Condition.OKAY)  # __init__ called
+    bike = Bike('Univega Alpina, orange', Condition.OKAY, sale_price=500, cost=100)
 
-    print(bike)     # __str__ called
+    print(bike)        # __str__ called
+    print(str(bike))   # __str__ called
 
-    print([bike])   # __repr__ called
+    print([bike])      # __repr__ called
+    print(repr(bike))  # __repr__ called
 
-    del bike        # __del__ called
+    del bike           # __del__ called
 
-    Bike(0, 'Raleigh', 'Talus 2', 2013, Condition.BAD)  # __init__ and __del__ called
+    bike = Bike('Raleigh Talus 2', Condition.BAD, sale_price=20)  # __init__ and __del__ called