David Bustos writes:

I have a ZClass named Event. Event objects need to keep a list of people signed up for them, so they had a lines property named 'people'. But lines properties have odd semantics, and I want to store arbitrary objects rather than strings (i.e. it shouldn't be edited through the web like a lines property is). So I would like for the 'people' attributes of Event objects to be regular Python lists. I would make the class folder-like and add the people as people ZInstances.

If you dislike only the editing through the web, then you are not obliged to make it available.

It seems that I should create this attribute in the Event_add constructor in my Product. But how do I do that? It is not forseen, that you add a list attribute to an object. However, in Python, you could do it.

Be careful, however! There are several caveats that may make it into a nightmare. One aspect (there may be more): The ZODB stores objects without (acquisition) context. Usually, the acquisition object is inherited from the parent object. However, lists, dictionaries etc. do not have an acquisition context. They can not inherit it to their components. Thus, if you access "list[i]", the resulting object does not have an acquisition context (if the list directly came from the ZODB) and the use of the resulting object is restricted. Dieter