Added a couple comments and an example of a property setter.

jslvtr · jslvtr · commit e484d25643d2 · 2018-03-05T22:04:27.000Z
diff --git a/section16/sample_code/4-abc-3-and-interfaces/saveable.py b/section16/sample_code/4-abc-3-and-interfaces/saveable.py
@@ -6,6 +6,7 @@ class Saveable(metaclass=ABCMeta):
     def save(self):
         Database.insert(self.to_dict())
     
-    @abstractmethod
+    # @classmethod (or @staticmethod, or @property)
+    @abstractmethod  # @abstractmethod must always be the innermost decorator if used in conjunction with other decorators.
     def to_dict():
         pass
diff --git a/section16/sample_code/5-property-setters/app.py b/section16/sample_code/5-property-setters/app.py
@@ -0,0 +1,14 @@
+from flight import Segment, Flight
+
+
+seg = [Segment('EDI', 'LHR'), Segment('LHR', 'CAN')]
+flight = Flight(seg)
+
+print(flight.departure_point)
+print(flight)
+
+flight.departure_point = 'GLA'
+print('...Set departure to GLA...')
+
+print(flight.departure_point)
+print(flight)
diff --git a/section16/sample_code/5-property-setters/flight.py b/section16/sample_code/5-property-setters/flight.py
@@ -0,0 +1,30 @@
+class Flight:
+    def __init__(self, segments):
+        """
+        Creates a new Flight wrapper object from an arbitrary number of segments.
+
+        :param segments: a list of segments in this flight—normally just one.
+        """
+        self.segments = segments
+    
+    def __repr__(self):
+        stops = [self.segments[0].departure, self.segments[0].destination]
+        for seg in self.segments[1:]:
+            stops.append(seg.destination)
+        
+        return ' -> '.join(stops)
+    
+    @property
+    def departure_point(self):
+        return self.segments[0].departure
+    
+    @departure_point.setter
+    def departure_point(self, val):
+        dest = self.segments[0].destination
+        self.segments[0] = Segment(departure=val, destination=dest)
+    
+
+class Segment:
+    def __init__(self, departure, destination):
+        self.departure = departure
+        self.destination = destination
