paula.proputil/src/paula/proputil/subscribers.py

   1 # Copyright (c) 2008 by Florian Friesdorf
   2 #
   3 # GNU Affero General Public License (AGPL)
   4 #
   5 # This program is free software; you can redistribute it and/or modify
   6 # it under the terms of the GNU Affero General Public License as
   7 # published by the Free Software Foundation; either version 3 of the
   8 # License, or (at your option) any later version.
   9 #
  10 # This program is distributed in the hope that it will be useful,
  11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
  12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  13 # GNU Affero General Public License for more details.
  14 #
  15 # You should have received a copy of the GNU Affero General Public
  16 # License along with this program.  If not, see
  17 # <http://www.gnu.org/licenses/>.
  18 """
  19 """
  20 __author__ = "Florian Friesdorf <flo@chaoflow.net>"
  21 __docformat__ = "plaintext"
  22
  23 from zope.app.container.interfaces import IObjectAddedEvent
  24 from zope.app.container.interfaces import IObjectRemovedEvent
  25
  26 from zope.component import adapter, queryUtility
  27
  28 from zope.location.interfaces import ILocation
  29
  30 from paula.properties.interfaces import IPropertyProvider
  31
  32 from paula.proputil.interfaces import IPropertyProviderAdaptable
  33 from paula.proputil.interfaces import IRWPropertyProviders
  34
  35
  36 @adapter(ILocation, IObjectAddedEvent)
  37 def checkRegister(obj, event):
  38     """A subscriber to ObjectAddedEvent
  39
  40     Registers an object with all nearest IRWPropertyProviders, iff
  41     IPropertyProviderAdaptable is provided by the object.
  42     """
  43     if not IPropertyProviderAdaptable.providedBy(obj) and \
  44             not IPropertyProvider.providedBy(obj):
  45         return
  46
  47     # we are registered globally and might run in a context without
  48     # IRWPropertyProviders
  49     util = queryUtility(IRWPropertyProviders) #, context=event.newParent)
  50     # XXX: not working, ppu is False?!
  51     #if ppu:
  52     if util is not None:
  53         util.register(obj)
  54
  55
  56 @adapter(ILocation, IObjectRemovedEvent)
  57 def checkUnregister(obj, event):
  58     """A subscriber to ObjectRemovedEvent
  59
  60     Unregisters an object from all nearest IRWPropertyProviders, iff
  61     IPropertyProviderAdaptable is provided by the object.
  62     """
  63     if not IPropertyProviderAdaptable.providedBy(obj) and \
  64             not IPropertyProvider.providedBy(obj):
  65         return
  66
  67     # we are registered globally and might run in a context without
  68     # IRWPropertyProviders
  69     util = queryUtility(IRWPropertyProviders) #, context=event.oldParent)
  70     # XXX: not working, ppu is False?!
  71     #if ppu:
  72     if util is not None:
  73         try:
  74             util.unregister(obj)
  75         except KeyError:
  76             pass