update from Atlas

08-obj-ref/bus.py

@@ -0,0 +1,29 @@
+
+"""
+>>> import copy
+>>> bus1 = Bus(['Alice', 'Bill', 'Claire', 'David'])
+>>> bus2 = copy.copy(bus1)
+>>> bus3 = copy.deepcopy(bus1)
+>>> bus1.drop('Bill')
+>>> bus2.passengers
+['Alice', 'Claire', 'David']
+>>> bus3.passengers
+['Alice', 'Bill', 'Claire', 'David']
+
+"""
+
+# BEGIN BUS_CLASS
+class Bus:
+
+    def __init__(self, passengers=None):
+        if passengers is None:
+            self.passengers = []
+        else:
+            self.passengers = list(passengers)
+
+    def pick(self, name):
+        self.passengers.append(name)
+
+    def drop(self, name):
+        self.passengers.remove(name)
+# END BUS_CLASS

08-obj-ref/cheese.py

@@ -0,0 +1,28 @@
+"""
+>>> import weakref
+>>> stock = weakref.WeakValueDictionary()
+>>> catalog = [Cheese('Red Leicester'), Cheese('Tilsit'),
+...                 Cheese('Brie'), Cheese('Parmesan')]
+...
+>>> for cheese in catalog:
+...     stock[cheese.kind] = cheese
+...
+>>> sorted(stock.keys())
+['Brie', 'Parmesan', 'Red Leicester', 'Tilsit']
+>>> del catalog
+>>> sorted(stock.keys())
+['Parmesan']
+>>> del cheese
+>>> sorted(stock.keys())
+[]
+"""
+
+# BEGIN CHEESE_CLASS
+class Cheese:
+
+    def __init__(self, kind):
+        self.kind = kind
+
+    def __repr__(self):
+        return 'Cheese(%r)' % self.kind
+# END CHEESE_CLASS

08-obj-ref/haunted_bus.py

@@ -0,0 +1,47 @@
+"""
+>>> bus1 = HauntedBus(['Alice', 'Bill'])
+>>> bus1.passengers
+['Alice', 'Bill']
+>>> bus1.pick('Charlie')
+>>> bus1.drop('Alice')
+>>> bus1.passengers
+['Bill', 'Charlie']
+>>> bus2 = HauntedBus()
+>>> bus2.pick('Carrie')
+>>> bus2.passengers
+['Carrie']
+>>> bus3 = HauntedBus()
+>>> bus3.passengers
+['Carrie']
+>>> bus3.pick('Dave')
+>>> bus2.passengers
+['Carrie', 'Dave']
+>>> bus2.passengers is bus3.passengers
+True
+>>> bus1.passengers
+['Bill', 'Charlie']
+
+
+>>> dir(HauntedBus.__init__)  # doctest: +ELLIPSIS
+['__annotations__', '__call__', ..., '__defaults__', ...]
+>>> HauntedBus.__init__.__defaults__
+(['Carrie', 'Dave'],)
+>>> HauntedBus.__init__.__defaults__[0] is bus2.passengers
+True
+
+"""
+
+# BEGIN HAUNTED_BUS_CLASS
+class HauntedBus:
+    """A bus model haunted by ghost passengers"""
+
+    def __init__(self, passengers=[]):  # <1>
+        self.passengers = passengers  # <2>
+
+    def pick(self, name):
+        self.passengers.append(name)  # <3>
+
+    def drop(self, name):
+        self.passengers.remove(name)
+# END HAUNTED_BUS_CLASS
+

08-obj-ref/twilight_bus.py

@@ -0,0 +1,26 @@
+"""
+>>> basketball_team = ['Sue', 'Tina', 'Maya', 'Diana', 'Pat']
+>>> bus = TwilightBus(basketball_team)
+>>> bus.drop('Tina')
+>>> bus.drop('Pat')
+>>> basketball_team
+['Sue', 'Maya', 'Diana']
+"""
+
+# BEGIN TWILIGHT_BUS_CLASS
+class TwilightBus:
+    """A bus model that makes passengers vanish"""
+
+    def __init__(self, passengers=None):
+        if passengers is None:
+            self.passengers = []  # <1>
+        else:
+            self.passengers = passengers  #<2>
+
+    def pick(self, name):
+        self.passengers.append(name)
+
+    def drop(self, name):
+        self.passengers.remove(name)  # <3>
+# END TWILIGHT_BUS_CLASS
+