python的魔术方法

__str__

描述类的实例 print example

__repr__

描述类 print Example

__call__

调用实例 example() #=Example()()

__setattr__

实例属性赋值

__getattr__

获取实例属性值

class Book(object):
def __setattr__(self, name, value):
if name == 'value':
object.__setattr__(self, name, value - 100)
else:
object.__setattr__(self, name, value)
def __getattr__(self, name):
try:
return object.__getattribute__(name)
except:
return name + ' is not found!'
def __str__(self):
return ' cost : ' + str(self.value)

c = Book()
c.value = 101
print c.value ＃1
print c
print c.Type

__slots__

类所能包含的所有新建属性，继承自object类