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2009年08月13日 星期四 06:48 P.M.
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
Python代码
[/url]
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
7.2 迭代重载
Python代码
[url=http://wangtong40.javaeye.com/blog/369429#]
class indexer:
def __getitem__(self, index): #iter override
return index ** 2
X = indexer()
X[2]
for i in range(5):
print X class indexer:
def __getitem__(self, index): #iter override
return index ** 2
X = indexer()
X[2]
for i in range(5):
print X
7.3 索引重载
Python代码
[/url]
class stepper:
def __getitem__(self, i):
return self.data
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
X = stepper()
X.data = 'Spam'
X[1] #call __getitem__
for item in X: #call __getitem__
print item
7.4 getAttr/setAttr重载
Python代码
[url=http://wangtong40.javaeye.com/blog/369429#]
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
7.5 打印重载
Python代码
[/url]
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__
7.6 Call调用函数重载
Python代码
[url=http://wangtong40.javaeye.com/blog/369429#]
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)
7.7 析构函数重载
Python代码
[/url]
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__
本文来自ChinaUnix博客,如果查看原文请点:[url]http://blog.chinaunix.net/u1/59571/showart_2071511.html |
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