Python3 操作符重载方法

本文由 Luzhuo 编写,转发请保留该信息.
原文: http://blog.csdn.net/Rozol/article/details/70769628
以下代码以Python3.6.1为例
Less is more!
操作符重载方法: 类(class)通过使用特殊名称的方法(len(self))来实现被特殊语法(len())的调用
#coding=utf-8# specialfuns.py 操作符重载方法# 类(class)通过使用特殊名称的方法(__len__(self))来实现被特殊语法(len())的调用# 构造 与 析构 方法class demo1:    # 构造方法, 对象实例化时调用    def __init__(self):        print("构造方法")    # 析构方法, 对象被回收时调用    def __del__(self):        print("析构方法")# newclass demo2(object):    # __init__之前调用, 一般用于重写父类的__new__方法, 具体使用见 类 文章的 元类 代码部分(http://blog.csdn.net/rozol/article/details/69317339)    def __new__(cls):        print("new")        return object.__new__(cls)# 算术运算class demo3:    def __init__(self, num):        self.data = num    # +    def __add__(self, other):        return self.data + other.data    # -    def __sub__(self, other):        return self.data - other.data    # *    def __mul__(self, other):        return self.data * other.data    # /    def __truediv__(self, other):        return self.data / other.data    # //    def __floordiv__(self, other):        return self.data // other.data    # %    def __mod__(self, other):        return self.data % other.data    # divmod()    def __divmod__(self, other):        # 商(10/5),余数(10%5)        return self.data / other.data, self.data % other.data    # **    def __pow__(self, other):        return self.data ** other.data    # <<    def __lshift__(self, other):        return self.data << other.data    # >>    def __rshift__(self, other):        return self.data >> other.data    # &    def __and__(self, other):        return self.data & other.data    # ^    def __xor__(self, other):        return self.data ^ other.data    # |    def __or__(self, other):        return self.data | other.dataclass none:    def __init__(self, num):        self.data = num# 反算术运算符(a+b, 若a不支持算术运算符,则寻找b的算术运算符)(注:位置变换, 在原始函数名前+r)class demo4:    def __init__(self, num):        self.data = num    # +    def __radd__(self, other):        return other.data + self.data    # -    def __rsub__(self, other):        return other.data - self.data    # *    def __rmul__(self, other):        return other.data * self.data    # /    def __rtruediv__(self, other):        return other.data / self.data    # //    def __rfloordiv__(self, other):        return other.data // self.data    # %    def __rmod__(self, other):        return other.data % self.data    # divmod()    def __rdivmod__(self, other):        return other.data / self.data, other.data % self.data    # **    def __rpow__(self, other):        return other.data ** self.data    # <<    def __rlshift__(self, other):        return other.data << self.data    # >>    def __rrshift__(self, other):        return other.data >> self.data    # &    def __rand__(self, other):        return other.data & self.data    # ^    def __rxor__(self, other):        return other.data ^ self.data    # |    def __ror__(self, other):        return other.data | self.data# 增量赋值运算,(注:位置同原始函数,在原始函数名前+i)class demo5():    def __init__(self, num):        self.data = num    # +=    def __iadd__(self, other):        return self.data + other    # -=    def __isub__(self, other):        return self.data - other    # *=    def __imul__(self, other):        return self.data * other    # /=    def __itruediv__(self, other):        return self.data / other    # //=    def __ifloordiv__(self, other):        return self.data // other    # %=    def __imod__(self, other):        return self.data % other    # **=    def __ipow__(self, other):        return self.data ** other    # <<=    def __ilshift__(self, other):        return self.data << other    # >>=    def __irshift__(self, other):        return self.data >> other    # &=    def __iand__(self, other):        return self.data & other    # ^=    def __ixor__(self, other):        return self.data ^ other    # |=    def __ior__(self, other):        return self.data | other# 比较运算符class demo6:    def __init__(self, num):        self.data = num    # <    def __lt__(self, other):        return self.data < other.data    # <=    def __le__(self, other):        return self.data <= other.data    # ==    def __eq__(self, other):        return self.data == other.data    # !=    def __ne__(self, other):        return self.data != other.data    # >    def __gt__(self, other):        return self.data > other.data    # >=    def __ge__(self, other):        return self.data >= other.data# 一元操作符class demo7:    def __init__(self, num):        self.data = num    # + 正号    def __pos__(self):        return +(self.data)    # - 负号    def __neg__(self):        return -abs(self.data)    # abs() 绝对值    def __abs__(self):        return abs(self.data)    # ~ 按位取反    def __invert__(self):        return ~self.data    # complex() 字符转数字    def __complex__(self):        return 1+2j    # int() 转为整数    def __int__(self):        return 123    # float() 转为浮点数    def __float__(self):        return 1.23    # round()  近似值    def __round__(self):        return 1.123# 格式化class demo8:    # print() 打印    def __str__(self):        return "This is the demo."    # repr() 对象字符串表示    def __repr__(self):        return "This is a demo."    # bytes() 对象字节字符串表现形式    def __bytes__(self):        return b"This is one demo."    # format() 格式化    def __format__(self, format_spec):        return self.__str__()# 属性访问class demo9:    # 获取(不存在)属性    def __getattr__(self):        print ("访问的属性不存在")    # getattr() hasattr() 获取属性    def __getattribute__(self, attr):        print ("访问的属性是%s"%attr)        return attr    # setattr() 设置属性    def __setattr__(self, attr, value):        print ("设置 %s 属性值为 %s"%(attr, value))    # delattr() 删除属性    def __delattr__(self, attr):        print ("删除 %s 属性"%attr)# ===================================================================# 描述器(类(test1)的实例出现在属主类(runtest)中,这些方法才会调用)(注:函数调用,这些方法不会被调用)class test1:    def __init__(self, value = 1):        self.value = value * 2    def __set__(self, instance, value):        print("set %s %s %s"%(self, instance, value))        self.value = value * 2    def __get__(self, instance, owner):        print("get %s %s %s"%(self, instance, owner))        return self.value    def __delete__(self, instance):        print("delete %s %s"%(self, instance))        del self.valueclass test2:    def __init__(self, value = 1):        self.value = value + 0.3    def __set__(self, instance, value):        print("set %s %s %s"%(self, instance, value))        instance.t1 = value + 0.3    def __get__(self, instance, owner):        print("get %s %s %s"%(self, instance, owner))        return instance.t1    def __delete__(self, instance):        print("delete %s %s"%(self, instance))        del self.valueclass runtest:    t1 = test1()    t2 = test2()# ---# 自定义propertyclass property_my:    def __init__(self, fget=None, fset=None, fdel=None):        self.fget = fget        self.fset = fset        self.fdel = fdel    # 对象被获取(self自身, instance调用该对象的对象(demo9), owner调用该对象的对象类对象(demo9))    def __get__(self, instance, owner):        print("get %s %s %s"%(self, instance, owner))        return self.fget(instance)    # 对象被设置属性时    def __set__(self, instance, value):        print("set %s %s %s"%(self, instance, value))        self.fset(instance, value)    # 对象被删除时    def __delete__(self, instance):        print("delete %s %s"%(self, instance))        self.fdel(instance)class demo10:    def __init__(self):        self.num = None    def setvalue(self, value):        self.num = value    def getvalue(self):        return self.num    def delete(self):        del self.num    x = property_my(getvalue, setvalue, delete)# ===================================================================# 自定义容器class lis:    def __init__(self, *args):        self.lists = args        self.size = len(args)        self.startindex = 0        self.endindex = self.size    # len() 容器元素数量    def __len__(self):        return self.size;    # lis[1] 获取元素    def __getitem__(self, key = 0):        return self.lists[key]    # lis[1] = value 设置元素    def __setitem__(self, key, value):        pass    # del lis[1] 删除元素    def __delitem__(self, key):        pass    # 返回迭代器    def ____(self):        return self    # rversed() 反向迭代器    def __reversed__(self):        while self.endindex > 0:            self.endindex -= 1            yield self[self.endindex]    # next() 迭代器下个元素    def __next__(self):        if self.startindex >= self.size:            raise StopIteration # 控制迭代器结束        elem = self.lists[self.startindex]        self.startindex += 1        return elem    # in / not in    def __contains__(self, item):        for i in self.lists:            if i == item:                return True        return False# yield 生成器(执行一次返回,下次继续执行后续代码返回)def yielddemo():    num = 0    while 1: # 1 == True; 0 == False        if num >= 10:            raise StopIteration        num += 1        yield num# 能接收数据的生成器def yielddemo_1():    while 1:        num = yield        print(num)# with 自动上下文管理class withdemo:    def __init__(self, value):        self.value = value    # 返回值为 as 之后的值    def __enter__(self):        return self.value    # 执行完成,退出时的数据清理动作    def __exit__(self, exc_type, exc_value, traceback):        del self.valueif __name__ == "__main__":    # 构造与析构    d1 = demo1()    del d1    # new    d2 = demo2()    # 算术运算符    d3 = demo3(3)    d3_1 = demo3(5)    print(d3 + d3_1)    print(d3 - d3_1)    print(d3 * d3_1)    print(d3 / d3_1)    print(d3 // d3_1)    print(d3 % d3_1)    print(divmod(d3, d3_1))    print(d3 ** d3_1)    print(d3 << d3_1)    print(d3 >> d3_1)    print(d3 & d3_1)    print(d3 ^ d3_1)    print(d3 | d3_1)    # 反运算符    d4 = none(3)    d4_1 = demo4(5)    print(d4 + d4_1)    print(d4 - d4_1)    print(d4 * d4_1)    print(d4 / d4_1)    print(d4 // d4_1)    print(d4 % d4_1)    print(divmod(d4, d4_1))    print(d4 ** d4_1)    print(d4 << d4_1)    print(d4 >> d4_1)    print(d4 & d4_1)    print(d4 ^ d4_1)    print(d4 | d4_1)    # 增量赋值运算(测试时注释其他代码)     = demo5(3)    d5 <<= 5    d5 >>= 5    d5 &= 5    d5 ^= 5    d5 |= 5    d5 += 5    d5 -= 5    d5 *= 5    d5 /= 5    d5 //= 5    d5 %= 5    d5 **= 5    print(d5)    # 比较运算符    d6 = demo6(3)    d6_1 = demo6(5)    print(d6 < d6_1)    print(d6 <= d6_1)    print(d6 == d6_1)    print(d6 != d6_1)    print(d6 > d6_1)    print(d6 >= d6_1)    # 一元操作符(测试时注释其他代码)    d7 = demo7(-5)    num = +d7    num = -d7    num = abs(d7)    num = ~d7    print(num)    print(complex(d7))    print(int(d7))    print(float(d7))    print(round(d7))    # 格式化    d8 = demo8()    print(d8)    print(repr(d8))    print(bytes(d8))    print(format(d8, ""))    # 属性访问    d9 = demo9()    setattr(d9, "a", 1) # => 设置 a 属性值为 1    print(getattr(d9, "a")) # => a / 访问的属性是a    print(hasattr(d9, "a")) # => True / 访问的属性是a    delattr(d9, "a") # 删除 a 属性    # ---    d9.x = 100 # => 设置 x 属性值为 100    print(d9.x) # => x / 访问的属性是x    del d9.x # => 删除 x 属性    # 描述器    r = runtest()    r.t1 = 100 # =>  <__main__.test1> <__main__.runtest> 100    print(r.t1) # => 200 /  <__main__.test1> <__main__.runtest> 
     
          del r.t1 # =>  <__main__.test1> <__main__.runtest>    r.t2 = 200 # => <__main__.test2> <__main__.runtest> 200 / <__main__.test1> <__main__.runtest> 200.3    print(r.t2) # => 400.6 / <__main__.test2> <__main__.runtest> 
      
        /  <__main__.test1> <__main__.runtest> 
       
            del r.t2 # <__main__.test2> <__main__.runtest>    # ---    # 自定义property    d10 = demo10()    d10.x = 100; # => <__main__.property_my> <__main__.demo10> 100    print(d10.x) # => 100 / <__main__.property_my> <__main__.demo10> 
        
             del d10.x # => <__main__.property_my> <__main__.demo10>    d10.num = 200;    print(d10.num) # => 200    del d10.num    # 自定义容器(迭代器Iterator)    lis = lis(1,2,3,4,5,6)    print(len(lis))    print(lis[1])    print(next(lis))    print(next(lis))    print(next(lis))    for i in lis:        print (i)    for i in reversed(lis):        print (i)    print(3 in lis)    print(7 in lis)    print(3 not in lis)    print(7 not in lis)    # yield 生成器(可迭代对象Iterable)    for i in yielddemo():        print (i)    # ---    iters = iter(yielddemo())    print(next(iters))    print(next(iters))    # --- 发送数据给生成器 ---    iters = yielddemo_1()    next(iters)    iters.send(6) # 发送数据并执行    iters.send(10)    # with 自动上下文管理    with withdemo("Less is more!") as s:        print(s)
转载于:https://www.cnblogs.com/langqi250/p/10491861.html
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