decorator - Why does @foo.setter in Python not work for me? -

so, i'm playing decorators in python 2.6, , i'm having trouble getting them work. here class file:

class testdec:      @property     def x(self):          print 'called getter'         return self._x      @x.setter     def x(self, value):          print 'called setter'         self._x = value 

what thought meant treat x property, call these functions on , set. so, fired idle , checked it:

>>> testdec import testdec testdec import testdec >>> t = testdec() t = testdec() >>> t.x t.x called getter traceback (most recent call last):   file "<stdin>", line 1, in <module>   file "testdec.py", line 18, in x     return self._x attributeerror: testdec instance has no attribute '_x' >>> t.x = 5 t.x = 5 >>> t.x t.x 5 

clearly first call works expected, since call getter, , there no default value, , fails. ok, good, understand. however, call assign t.x = 5 seems create new property x, , getter doesn't work!

what missing?

you seem using classic old-style classes. in order properties work correctly need use new-style classes instead (inherit object). declare class myclass(object):

class testdec(object):      @property     def x(self):          print 'called getter'         return self._x      @x.setter     def x(self, value):          print 'called setter'         self._x = value 

it works:

>>> k = testdec() >>> k.x called getter traceback (most recent call last):   file "<stdin>", line 1, in <module>   file "/devel/class_test.py", line 6, in x     return self._x attributeerror: 'testdec' object has no attribute '_x' >>> k.x = 5 called setter >>> k.x called getter 5 >>>