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??????????????????Python??????????????????????????????????????????????????????????????????????

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?Python????????????????????????????????__??????????????????????????????????????

?????????????JustCounter???__secretCount???????publicCount???????

class JustCounter:    __secretCount = 0  # ????    publicCount = 0    # ????    def count(self):        self.__secretCount += 1        self.publicCount += 1        print(self.__secretCount)

????counter = JustCounter()?????

• count()?????????1
• publicCount?????????2
• ????__secretCount???AttributeError?????????

??????????????Python????????????????????????????????

• print(counter._JustCounter__secretCount)????????
• ?print(counter.__secretCount)??????

????

?Python???????BIF?Built-in Functions????????????????????????????????????????

1. issubclass()

issubclass(class, classinfo)????class???classinfo??????????????????classinfo????????????????????

???

class A:    passclass B(A):    passprint(issubclass(B, A))  # ??Trueprint(issubclass(B, B))  # ??Trueprint(issubclass(A, B))  # ??Falseprint(issubclass(B, object))  # ??True

2. isinstance()

isinstance(object, classinfo)?????????????????? inheritance chain??type()???isinstance()????????

???

a = 2print(isinstance(a, int))  # ??Trueprint(isinstance(a, str))  # ??Falseprint(isinstance(a, (str, int, list)))  # ??Trueclass A:    passclass B(A):    passprint(isinstance(A(), A))  # ??Trueprint(type(A()) == A)  # ??Trueprint(isinstance(B(), A))  # ??Trueprint(type(B()) == A)  # ??False

3. hasattr()

hasattr(object, name)????????????????

???

class Coordinate:    x = 10    y = -5    z = 0point1 = Coordinate()print(hasattr(point1, 'x'))  # ??Trueprint(hasattr(point1, 'y'))  # ??Trueprint(hasattr(point1, 'z'))  # ??Trueprint(hasattr(point1, 'no'))  # ??False

4. getattr()

getattr(object, name, default)?????????????????

???

class A(object):    bar = 1a = A()print(getattr(a, 'bar'))  # ??1print(getattr(a, 'bar2', 3))  # ??3print(getattr(a, 'bar2'))  # ??AttributeError

5. setattr()

setattr(object, name, value)?????????????????????

???

class A(object):    bar = 1a = A()print(getattr(a, 'bar'))  # ??1setattr(a, 'bar', 5)print(a.bar)  # ??5setattr(a, "age", 28)print(a.age)  # ??28

6. delattr()

delattr(object, name)??????????

???

class Coordinate:    x = 10    y = -5    z = 0point1 = Coordinate()print('x = ', point1.x)  # ??x = 10print('y = ', point1.y)  # ??y = -5print('z = ', point1.z)  # ??z = 0delattr(Coordinate, 'z')print('--?? z ???--')  # ??--?? z ???--print('x = ', point1.x)  # ??x = 10print('y = ', point1.y)  # ??y = -5

7. property()

property([fget[, fset[, fdel[, doc]]])????????????????fget?fset?fdel??????????????????????

???

class C(object):    def __init__(self):        self.__x = None    def getx(self):        return self.__x    def setx(self, value):        self.__x = value    def delx(self):        del self.__x    x = property(getx, setx, delx, "I'm the 'x' property.")cc = C()cc.x = 2print(cc.x)  # ??2del cc.xprint(cc.x)  # ??AttributeError

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