類的專有方法：

??? __init__ 構造函數，在生成對象時調用

??? __del__ 析構函數，釋放對象時使用

??? __repr__ 打印，轉換

??? __setitem__按照索引賦值

??? __getitem__按照索引獲取值

??? __len__獲得長度

??? __cmp__比較運算

??? __call__函數調用

??? __add__加運算

??? __sub__減運算

??? __mul__乘運算

??? __div__除運算

??? __mod__求余運算

??? __pow__稱方

?

?

class BaseClass: def __init__(self): self.name = 'BaseClass' print('BaseCalss: Constructor called') def getname(self): print('BaseCalss: self name equals ' + self.name) ? class DerivedClass(BaseClass): def __init__(self): super().__init__() print('DerivedClass: Constructor called') ? if __name__ == '__main__': class1 = BaseClass() class1.getname() class2 = DerivedClass() class2.getname()

運行結果：

BaseCalss: Constructor called BaseCalss: self name equals BaseClass BaseCalss: Constructor called DerivedClass: Constructor called BaseCalss: self name equals BaseClass

?

子類也可以overwrite父類的方法，那么父類的方法就不會被調用，除非手動調用：

class BaseClass: def __init__(self): self.name = 'BaseClass' print('BaseCalss: Constructor called') def getname(self): print('BaseCalss: self name equals ' + self.name) ? class DerivedClass(BaseClass): def __init__(self): super().__init__() print('DerivedClass: Constructor called') def getname(self): print('self.name init value is ' + self.name) self.name = 'DerivedClass' print('DerivedClass: self name equals ' + self.name) ? if __name__ == '__main__': class1 = BaseClass() class1.getname() class2 = DerivedClass() class2.getname()

?

運行結果：

BaseCalss: Constructor called?
BaseCalss: self name equals BaseClass?
BaseCalss: Constructor called?
DerivedClass: Constructor called?
self.name init value is BaseClass?
DerivedClass: self name equals DerivedClass

?

python不僅僅支持單繼承，還支持多繼承

? class BaseClass1:

def __init__(self): self.name1 = 'BaseClass1_Name1' self.name = 'BaseClass1_Name' print('BaseCalss1: Constructor called') def getname1(self): print('BaseCalss1: self name1 equals ' + self.name1) def getname(self): print('BaseCalss1: getname called, name equal ' + self.name) ? class BaseClass2: def __init__(self): self.name2 = 'BaseClass2_Name2' self.name = 'BaseClass2_Name' print('BaseClass2: Constructor called') def getname2(self): print('BaseClass2: self name2 equals ' + self.name2) def getname(self): print('BaseCalss2: getname called, name equal ' + self.name) ? class DerivedClass2(BaseClass1, BaseClass2): def __init__(self): BaseClass1.__init__(self) BaseClass2.__init__(self) print('DerivedClass: Constructor called') if __name__ == '__main__': class1 = BaseClass1() class1.getname1() class2 = BaseClass2() class2.getname2() class3 = DerivedClass2() class3.getname1() class3.getname2() class3.getname()

運行結果：

BaseCalss1: Constructor called?
BaseCalss1: self name1 equals BaseClass1_Name1?
BaseClass2: Constructor called?
BaseClass2: self name2 equals BaseClass2_Name2?
BaseCalss1: Constructor called?
BaseClass2: Constructor called?
DerivedClass: Constructor called?
BaseCalss1: self name1 equals BaseClass1_Name1?
BaseClass2: self name2 equals BaseClass2_Name2?
BaseCalss1: getname called, name equal BaseClass2_Name

?

轉載于:https://www.cnblogs.com/jnbb/p/8316273.html

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