Lucasm <lordlucr...@gmail.com> writes: > Thanks for the answers. I would like to override the property though > without making special modifications in the main class beforehand. Is > this possible?
That will not be easy. When you access obj.return_five, python looks up 'return_five' in type(obj) to see what the return_five property even means. (See http://users.rcn.com/python/download/Descriptor.htm for details of how this works.) Since you can't change the source of A, you are left with two options: you can monkey-patch A.return_five to make it optionally consult the instance, or you can assign to instance's __class__ to make it point to a subclass of A that implements a different 'return_five'. Both options are fairly unpleasant, but I think I'd go with the first one. Others have spelled out the __class__-changing variant. While monkey-patching is not the cleanest of practices to adopt, in my mind it still beats assigning to __class__. Here is an example: # Wrap return_five so it supports per-instance customization, but # without copy-pasting the original. def wrap_return_five(orig): @property def wrapper(self): if 'return_five' in self.__dict__: return self.__dict__['return_five'] return orig.__get__(self, type(self)) return wrapper >>> A.return_five = wrap_return_five(A.return_five) >>> a = A() >>> b = A() >>> a.return_five 5 >>> a.__dict__['return_five'] = 10 >>> a.return_five 10 >>> b.return_five 5 If you want, you can make a.return_five itself settable, but I'll leave that as an excercise for the reader. -- http://mail.python.org/mailman/listinfo/python-list
