Hello, I was going through the zope book's chapter "Extending Zope" and I implemented a method called feed (the animal in a ZooExhibit). This method is not in the book, and I coded it as: from DateTime import DateTime context.propertysheets.ExhibitProperties.manage_changeProperties(last_meal_t ime = DateTime()) return context.index_html() This works, but my first (unsuccessfull) try was: from DateTime import DateTime context.last_meal_time = DateTime() return context.index_html() This gives an error: Error Type: TypeError Error Value: attribute-less object (assign or del) Why is last_meal_time not an attribute of the instance? In another method, isHungry, from the book, I can retrieve its value: if (DateTime().timeTime() - context.last_meal_time.timeTime() > 60 * 60 * 8): What's going on? Also, is there any difference between using container and context for an instance of a ZClass? Thanks, Fernando