Интересный Python - Вопрос 1, Python 3

Интересный Python - Вопрос 1

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print('look carefully for object identities')

print('\ndefine Inner')
class Inner:
    def __init__(self):
        print('Inner.__init__(', self, ')')
        
    def __del__(self):
        print('Inner.__del__(', self, ')')

print('\ndefine Outer')
class Outer:
    class_attribute = Inner()
    
    def __init__(self):
        print('Outer.__init__(', self, ')')
        self.instance_attribute = Inner()
        
    def __del__(self):
        print('Outer.__del__(', self, ')')

print('\ncreate OuterInstanceA')
OuterInstanceA = Outer()

print('\ncreate OuterInstanceB')
OuterInstanceB = Outer()

print('\nOuterInstanceA.class_attribute ::', OuterInstanceA.class_attribute)
print('OuterInstanceA.instance_attribute ::', OuterInstanceA.instance_attribute)
print('OuterInstanceB.class_attribute ::', OuterInstanceB.class_attribute)
print('OuterInstanceB.instance_attribute ::', OuterInstanceB.instance_attribute)
print('Outer.class_attribute ::', Outer.class_attribute)
try:
    print('Outer.instance_attribute ::', Outer.instance_attribute)
except Exception as e:
    print('Outer.instance_attribute !', e)

print('\ndelete OuterInstanceA')
del OuterInstanceA

print('\ndelete OuterInstanceB')
del OuterInstanceB

print('\ndelete Outer')
del Outer

print('\nend')

[ + ] Show input
Absolute running time: 0.41 sec, cpu time: 0.16 sec, memory peak: 6 Mb, absolute service time: 0,41 sec

look carefully for object identities define Inner define Outer Inner.__init__( <__main__.Inner object at 0x7fdecd8a54a8> ) create OuterInstanceA Outer.__init__( <__main__.Outer object at 0x7fdecc31e780> ) Inner.__init__( <__main__.Inner object at 0x7fdecc31e7b8> ) create OuterInstanceB Outer.__init__( <__main__.Outer object at 0x7fdecc31e828> ) Inner.__init__( <__main__.Inner object at 0x7fdecc31e860> ) OuterInstanceA.class_attribute :: <__main__.Inner object at 0x7fdecd8a54a8> OuterInstanceA.instance_attribute :: <__main__.Inner object at 0x7fdecc31e7b8> OuterInstanceB.class_attribute :: <__main__.Inner object at 0x7fdecd8a54a8> OuterInstanceB.instance_attribute :: <__main__.Inner object at 0x7fdecc31e860> Outer.class_attribute :: <__main__.Inner object at 0x7fdecd8a54a8> Outer.instance_attribute ! type object 'Outer' has no attribute 'instance_attribute' delete OuterInstanceA Outer.__del__( <__main__.Outer object at 0x7fdecc31e780> ) Inner.__del__( <__main__.Inner object at 0x7fdecc31e7b8> ) delete OuterInstanceB Outer.__del__( <__main__.Outer object at 0x7fdecc31e828> ) Inner.__del__( <__main__.Inner object at 0x7fdecc31e860> ) delete Outer end Inner.__del__( <__main__.Inner object at 0x7fdecd8a54a8> )