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 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 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, 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
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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