[Zope-dev] FW: ZPatterns, ObjectDomain, UML and all that.....

[RC Compaan]

(forgot to cc this to zope-dev)

-----Original Message-----
From: RC Compaan [mailto:sparroy@adept.co.za]
Sent: 05 December 2000 03:17
To: steve@spvi.com
Subject: RE: ZPatterns, ObjectDomain, UML and all that.....



> Thanks... is that working between transactions? It has me a little
> confused.  I've been snooping through the implementation of ZPatterns
> for a clue.... and it looks to me like:

Well so far it seems to work fine... I do however receive a KeyError with
one of my Dataskins but this is isolated to one particular Dataskin.  I did
not inspect the innards of ZPatterns that well, I must say, so this issue
still remains unresolved to me as well.

>  a) the data manager for a DataSkin is a non-persistent attribute.
>     (self._v_dm_). I think this means that it needs to be set
>     somehow in every Zope transaction before you can do much of
>     anything with the instance.

If this is the case then my current implementation will have to change quite
dramatically :(  I don't quite understand why Dataskins are implemented in
this way - this obstructs natural object oriented programming?  I would have
thought that the datamanager is set when the a Dataskin is created.

>     RC> With Container/Content type objects I do roughly the same - I
>     RC> have setContainer methods for the Content objects.
>
> So most of your objects are defined in Python products, or are these
> methods ExternalMethods?

They are all external methods - I do most of my development with ZClasses
and Python Methods make life a lot easier.

Roché

PS: I checked Rack.py:

CreateItem call _RawItem and in _RawItem the Rack for that instance is set:
 item._setRack(Self)  # Connect to Rack

I might be wrong but after a quick look at the attributehandling code in
Dataskins.py suggests that the Dataskin does not know who its datamanager
is.