[Zope3-Users] What attributes are made persistent

[Shaun Cutts]

Well, one could have a base class along the lines of

class PersistSetItemOnAttributes:

    def __setattr__( self, attr, val ):
        oldSI = val.__class__.__dict__.get( '__setitem__', None )
        if oldSI is not None:
            def newSI( vself, vattr, vval ):
                vself._p_changed = True     # is this the right member?
                oldSI( vattr, vval )        # oldSI is bound: no vself?
            val.__class__.__setitem__ = newSI
        super( PersistSetItemOnAttributes, self ).__setattr__( attr, val
)

Of course, this is really just pseudocode. For one thing, need to trap
whether 'val' is really a class. For another if you were serious about
this, you would want to check if the obj wasn't persistent first, and
you might want to do it recursively. And while your are at it, you might
want to check on other mutators as well....(for instance, check first
what sequence interface if any 'val' supports...)

... sounds like too much work, and would be problem prone even so. After
all, some things you don't want to be persistent!

- Shaun
 
> -----Original Message-----
> From: zope3-users-bounces at zope.org
[mailto:zope3-users-bounces at zope.org]
> On Behalf Of Stephan Richter
> Sent: Wednesday, February 15, 2006 8:43 AM
> To: zope3-users at zope.org
> Cc: Florian Lindner
> Subject: Re: [Zope3-Users] What attributes are made persistent
> 
> On Wednesday 15 February 2006 08:21, Peter Bengtsson wrote:
> > class PersistentAnything(PersistentMapping, PersistentList,
> > PersistentDict):
> 
> AAhhhh! This is so wrong! It merges two incompatible APIs: collections
and
> mappings. The non-persistent equivalent to this is:
> 
>   >>> class DoEverything(set, list, dict):
>   ...  pass
> 
> > Am I just trying to make it too simple?
> 
> I think you try far too hard to not understand why the persistent
> mechanism
> works as it does. You make your life harder than it has to be.
> 
> Regards,
> Stephan
> --
> Stephan Richter
> CBU Physics & Chemistry (B.S.) / Tufts Physics (Ph.D. student)
> Web2k - Web Software Design, Development and Training
> _______________________________________________
> Zope3-users mailing list
> Zope3-users at zope.org
> http://mail.zope.org/mailman/listinfo/zope3-users