[ZODB-Dev] Re: false write conflicts

[Marius Gedminas]

On Tue, Mar 02, 2004 at 11:15:42AM -0500, John Belmonte wrote:
> That is arguably a Python wart.  With regard to the containing object, 
> it seems unfortunate to consider "foo.bar +=1" different than 
> "foo.bar[a] = b".
> 
> This wrapper for Persistent.__setattr__ looks like it will suit my needs:
> 
>   class MyPersistent(Persistent):
>     def __setattr__(self, key, val):
>       if not (self.__dict__.has_key(key) and self.__dict__[key] is val):
>         Persistent.__setattr__(self, key, val)

I've seen a recommendation somewhere that it is better to write

  self.attr[x] = y
  self.attr = self.attr      # notify Persistence that something changed

than

  self.attr[x] = y
  self._p_changed = True     # notify Persistence that something changed

Your wrapper would hide the assignment in the first snippet from Persistence,
negating its purpose.

Marius Gedminas
-- 
If nothing else helps, read the documentation.
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