运算符重载
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],
For If
__len__ 长度 len(X)
__cmp__ 比较 X==Y,X
__lt__ 小于 X
__eq__ 等于 X=Y
__radd__ Right-Side + +X
__iadd__ += X+=Y
__iter__ 迭代 For In
__unicode__ unicode(X)
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]
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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
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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
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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
self.__dict__[attr] = value
else:
print attr
raise AttributeError, attr + 'not allowed'
X = accesscontrol()
X.age = 40 #call __setattr__
X.name = 'wang' #raise exception
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unicode重载
#coding:utf-8
class adder:
def __unicode__(self):
return u'hello world'
print unicode(x) #hello world
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