类，类对象和实例对象（第十四章）

>>> class C:
...     count = 0
...
>>> a = C()
>>> b = C()
>>> c = C()
>>> print(a.count,b.count,c.count)
0 0 0
>>> c.count +=100
>>> print(a.count,b.count,c.count)
0 0 100
>>> C.count +=100
>>> print(a.count,b.count,c.count)
100 100 100

>>> class C:
...     def x(self):
...             print("xman")#如果属性跟方法名相同，属性会覆盖方法
...

>>> c = C()

>>> c.x()
xman

>>> c.x = 1#覆盖

>>> c.x()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'int' object is not callable

>>> c.x#覆盖后属性为1 ，也即是变量会覆盖函数
1
>>>

printEmployeePaychecks()；
print_employee_paychecks()；

>>> class CC:
...     def setXY(self,x,y):
...             self.x = x
...             self.y = y
...     def printXY(self):
...             print(self.x,self.y)
...
>>> dd = CC()
>>> dd.setXY(2,4)
>>> dd.printXY()
2 4
>>>

>>> class CC:
...     def setXY(self,x,y):
...             self.x = x
...             self.y = y
...     def printXY(self):
...             print(self.x,self.y)
...
>>> dd = CC()
>>> dd.setXY(2,4)
>>> dd.printXY
<bound method CC.printXY of <__main__.CC object at 0x02AA1D30>>
>>> dd.printXY()
2 4
>>> dd.__dict__
{'y': 4, 'x': 2}
>>> CC.__dict__
mappingproxy({'printXY': <function CC.printXY at 0x02AA4228>, '__dict__': <attribute '__dict__' of 'CC' objects>, '__weakref__': <attribute '__weakref__' of 'CC' objects>, '__doc__': None, 'setXY': <function CC.setXY at 0x02AA4270>, '__module__': '__main__'})
>>>

>>> dd.printXY()
2 4
>>> dd.__dict__
{'y': 4, 'x': 2}

>>> CC.__dict__
mappingproxy({'printXY': <function CC.printXY at 0x02AA4228>, '__dict__': <attribute '__dict__' of 'CC' objects>, '__weakref__': <attribute '__weakref__' of 'CC' objects>, '__doc__': None, 'setXY': <function CC.setXY at 0x02AA4270>, '__module__': '__main__'})