Class update detection

[Miki Tebeka]

Hello Steven,

> I need to determine if 
> any of the class attributes have been changed to I can issue an update 
> query to the database with the changes.  Is there a generally accepted 
> method to do this?   Is there some way to create a checksum of the class 
> attributes?
Do you mean something in the lines of:
class C:
     def __init__(self, a, b):
         self.a, self.b = a, b
         self.dirty = 0
     def __setattr__(self, k, v):
         if k in ("a", "b"):
             self.dirty = 1
         self.__dict__[k] = v
 >> c = C(1,2)
 >>> c.dirty
0
 >>> c.a = 10
 >>> c.a
10
 >>> c.dirty
1
 >>>

Another option is to generate a checksum (using md5 and str) on all the 
attributes you're interested in at the end of __init__ and a function 
`dirty' will compute this checksum and return 1 if it was changed.
Note that if you have nested objects this might be a problem.

HTH.
Miki