[Zope] Extend copy/move protocol to object instantiation?

[Brian Lloyd]

> The copy/move protocol in 'CopySupport.py' is quite nice in that it
> allows the object which is being moved/copied to participate in the
> operation, including rejecting the operation or cleaning up at the
> conclusion of the operation. I found a need for something 
> similar when 
> objects are first installed in a folder(ish) location: 'scope out
> the neighborhood' and  'make yourself at home' hooks.
> 
> -----------------------------------------------------
> 
> class anyClass:
> 
>     ...
> 
>     def addsubs(self):
>         '''add sub category field names'''
>         resobj=self.aq_parent.catlist1()
>         res =[]
>         for field in resobj._searchable_result_columns():
>             res.append(field)
>         self.fields=res
> 
>     def makeyourselfathome(self):
>         """parent specific installation hook"""
>         self.addsubs()
>                        
> def addAnyClassObject(self,id,title,REQUEST=None):
>     """Create an Object and install it in its parent Folder	
>     The argument 'self' will be bound to the parent Folder.
>     """
>     ob=anyClass(id)
>     self._setObject(id, ob)
>     ob.__of__(self).makeyourselfathome()
>     if REQUEST is not None:
>         return self.manage_main(self,REQUEST)
> 
> -------------------------------------------------------------
> 
> Would it make sense to add another 'op' type to
> CopySource._NotifyOfCopyTo() and CopySource._postCopy() to indicate a
> 'first home' operation?
> 
> MAM

I'd much rather see an eventual Zope event model handle
things like this. In the absense of such a beast, we were
forced to come up with a workable solution for copy and paste,
but its probably not appropriate to try to make that general-
purpose.

I think it would be much better if you could eventually just
define "event handler" methods that interact with a well-known
event model to deal with such things, a la:

  def onObjectAdd(self, event):
      # Somehow use information in the event to
      # do some fixup on the added object, etc.
      ...

  def onCopyBegin(self, event):
      ...

  def onCopyFinish(self, event):
      ...




Brian Lloyd        brian@digicool.com
Software Engineer  540.371.6909              
Digital Creations  http://www.digicool.com