[ZDP] FAQ Entry addendum (was: RE: [Zope-dev] New Counter Product)

John Eikenberry John Eikenberry <jae@kavi.com>
Thu, 25 Mar 1999 11:08:14 -0800 (PST)

Previously posted question...

Shaw, Howard asked...

- How can I create a variable within a Product that will not be
  persistent (i.e. will not be written to disk)?
        (Michel Pelletier)
        Prefix your variable name with _v_.  If you don't want the
        attribute foo to be persistent, call it _v_foo.

	(Caveat from Paul Everitt) 
	But alas, there's a dark side to this. If you're object gets
	swapped out by the Zope cache manager, splat, there goes the
	updates since your last change.  Presumably it wouldn't be as it
	would be getting used a lot.

        (Pavlos Christoforou)
        ZODB cannot detect changes to mutable objects that are not treated
        as immutable. So I suppose that if your object includes a list, a 
        dictionary or a non persistence instance then any changes to these
        objects will go undetected by ZODB.


John Eikenberry
[jae@kavi.com - http://taos.kavi.com/~jae/] 
"A society that will trade a little liberty for a little order
 will deserve neither and lose both."
                                         --B. Franklin