[Python-Dev] The decorator(s) module

Sat Feb 11 14:29:07 CET 2006

Georg Brandl <g.brandl at gmx.net> wrote in news:dsj0p7$tk3$1 at sea.gmane.org:
> Unfortunately, a @property decorator is impossible...
>
It all depends what you want (and whether you want the implementation to be 
portable to other Python implementations). Here's one possible but not 
exactly portable example:
from inspect import getouterframes, currentframe
import unittest
class property(property):
 @classmethod
 def get(cls, f):
 locals = getouterframes(currentframe())[1][0].f_locals
 prop = locals.get(f.__name__, property())
 return cls(f, prop.fset, prop.fdel, prop.__doc__)
 @classmethod
 def set(cls, f):
 locals = getouterframes(currentframe())[1][0].f_locals
 prop = locals.get(f.__name__, property())
 return cls(prop.fget, f, prop.fdel, prop.__doc__)
 @classmethod
 def delete(cls, f):
 locals = getouterframes(currentframe())[1][0].f_locals
 prop = locals.get(f.__name__, property())
 return cls(prop.fget, prop.fset, f, prop.__doc__)
class PropTests(unittest.TestCase):
 def test_setgetdel(self):
 class C(object):
 def __init__(self, colour):
 self._colour = colour
 @property.set
 def colour(self, value):
 self._colour = value
 @property.get
 def colour(self):
 return self._colour
 @property.delete
 def colour(self):
 self._colour = 'none'
 
 inst = C('red')
 self.assertEquals(inst.colour, 'red')
 inst.colour = 'green'
 self.assertEquals(inst._colour, 'green')
 del inst.colour
 self.assertEquals(inst._colour, 'none')
if __name__=='__main__':
 unittest.main()