1 class Attr(object):
2
3 def __init__(self, name, type_):
4 self.name = name
5 self.type_ = type_
6
7 def __get__(self, instance, cls):
8 return instance.__dict__[self.name]
9
10 def __set__(self, instance, value):
11 if not isinstance(value, self.type_):
12 raise TypeError('expected an %s'% self.type_)
13
14 instance.__dict__[self.name] = value
15
16 def __delete__(self, instance):
17 del instance.__dict__[self.name]
18
19
20
21 class Person(object):
22 name = Attr('name', str)
23 age = Attr('age', int)
24 height = Attr('height', float)
25
26
27
28 p = Person()
29 p.name = 'ray'
30 print(p.name)
