Python运算符重载用法实例分析

概述本文实例讲述了Python运算符重载用法。分享给大家供大家参考。具体如下：在Python语言中提供了类似于C++的运算符重在功能：

本文实例讲述了Python运算符重载用法。分享给大家供大家参考。具体如下：

在Python语言中提供了类似于C++的运算符重在功能：

一下为Python运算符重在调用的方法如下：

Method         Overloads         Call for
__init__        构造函数         X=Class()
__del__         析构函数         对象销毁
__add__         +                 X+Y,X+=Y
__or__         |                 X|Y,X|=Y
__repr__        打印转换         print X，repr(X)
__str__         打印转换         print X，str(X)
__call__        调用函数         X()
__getattr_    限制             X.undefine
__setattr__     取值             X.any=value
__getitem__     索引             X[key]，
__len__         长度             len(X)
__cmp__         比较             X==Y,X<Y
__lt__         小于             X<Y
__eq__         等于             X=Y
__radd__        Right-SIDe +         +X
__iadd__        +=                 X+=Y
__iter__        迭代             For In

1. 减法重载

class Number:    def __init__(self,start):      self.data = start    def __sub__(self,other): #minus method      return Number(self.data - other)  number = Number(20)  y = number C 10 # invoke __sub__ method class Number:   def __init__(self,start):     self.data = start   def __sub__(self,other): #minus method     return Number(self.data - other) number = Number(20) y = number C 10 # invoke __sub__ method

2. 迭代重载

class indexer:    def __getitem__(self,index): #iter overrIDe      return index ** 2 X = indexer()  X[2]  for i in range(5):    print X[i] class indexer:   def __getitem__(self,index): #iter overrIDe     return index ** 2 X = indexer() X[2] for i in range(5):   print X[i]

3. 索引重载

class stepper:    def __getitem__(self,i):      return self.data[i]  X = stepper()  X.data = 'Spam' X[1] #call __getitem__  for item in X: #call __getitem__    print item class stepper:   def __getitem__(self,i):     return self.data[i] X = stepper() X.data = 'Spam' X[1] #call __getitem__ for item in X: #call __getitem__    print item

4. getAttr/setAttr重载

class empty:    def __getattr__(self,attrname):      if attrname == 'age':        return 40     else:        raise AttributeError,attrname  X = empty()  print X.age #call__getattr__  class accesscontrol:    def __setattr__(self,attr,value):      if attr == 'age':        # Self.attrname = value loops!        self.__dict__[attr] = value      else:        print attr        raise AttributeError,attr + 'not allowed' X = accesscontrol()  X.age = 40   #call __setattr__  X.name = 'wang' #raise exception class empty:   def __getattr__(self,attrname):     if attrname == 'age':       return 40     else:       raise AttributeError,attrname X = empty() print X.age #call__getattr__ class accesscontrol:   def __setattr__(self,value):     if attr == 'age':       # Self.attrname = value loops!       self.__dict__[attr] = value     else:       print attr       raise AttributeError,attr + 'not allowed' X = accesscontrol() X.age = 40   #call __setattr__ X.name = 'wang' #raise exception

5. 打印重载

class adder:    def __init__(self,value=0):      self.data = value    def __add__(self,other):      self.data += other  class addrepr(adder):    def __repr__(self):      return 'addrepr(%s)' % self.data  x = addrepr(2) #run __init__  x + 1    #run __add__  print x   #run __repr__ class adder:   def __init__(self,value=0):     self.data = value   def __add__(self,other):     self.data += other class addrepr(adder):   def __repr__(self):     return 'addrepr(%s)' % self.data x = addrepr(2) #run __init__ x + 1    #run __add__ print x   #run __repr__

6. Call调用函数重载

class Prod:    def __init__(self,value):      self.value = value    def __call__(self,other):      return self.value * other  p = Prod(2) #call __init__  print p(1) #call __call__  print p(2) class Prod:   def __init__(self,value):     self.value = value   def __call__(self,other):     return self.value * other p = Prod(2) #call __init__ print p(1) #call __call__ print p(2)

7. 析构函数重载

class life:    def __init__(self,name='name'):      print 'Hello',name      self.name = name    def __del__(self):      print 'Goodby',self.name  brain = life('Brain') #call __init__  brain = 'loretta'  # call __del__

希望本文所述对大家的Python程序设计有所帮助。

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