[Zope-PTK] content states

[Steve Alexander]

Steve Alexander wrote:
> 
>   * Does this multiple attribute thing really merit an interface of its
> own, rather than just an attributes and a method or two?

If we don't immediately go the ZPatterns way with this, here's a
straw-man interface. We should use an interface because it would make an
easy mix-in class, and Demeter's law suggests it's bad to just expose a
PersistentMapping, when we really want to say "this object has a
statespace".

  def ContentState(self):
  # For cataloguing as a KeywordIndex, sequence of strings
  # Example: ['review:published', 'readbyadmin:no']
  
  def ContentStateForMetaData(self):
  # Map of name:state, suitable for use as catalog metadata.
  # Example: {'review':'published', 'readbyadmin':'no'}
  
  def getStateFor(self, name):
  # Returns the state for a particular name
  # Example: obj.getStateFor('review') returns 'published'
  # Returns None if there is no state for that name.
  
  def changeState(self, name, newstate, reason=''):
  # Changes the state associated with name to newstate.
  # A reason may be recorded or auditing purposes.
  # sometimes the auditing subsystems will insist on
  # having a reason.
  # A new name:state gets created if none existed before.
  
  def delState(self, name, reason=''):
  # Like changeState, but removes the name
  # from the mapping.


Would namespaces be useful? I think so, if other subsystems get to
contribute to an object's state. Therefore, instead of the two-part
name:state as suggested above, we could have a three-part
namespace:name-state. For example, "reviewing:review-published".

 
--
Steve Alexander
Software Engineer
Cat-Box limited
 http://www.cat-box.net