Relationship properties

[jbailey]

My brain is drawing a blank on this:

Let's say I have a class Group and a class Person, where there's an n:m relationship between these. It's simple to say that Group could have an attribute "members" which is a collection of Persons, or Person could have an attribute "groups" which is a collection of Groups.

The problem then is that there's no relationship properties there. I can't easily describe for how long the person has been a member of the group, when that membership expires, etc. It seems to me that these type of properties ought to be describable in an elegant way. Perhaps as a characteristic of the array? I want to do this ideally in a way that for items that have no meaningful characteristics I can just use a standard Array class of some sort, but that when properties come up, I want to be able to add them silently so that existing code can continue to just work.

Comments

[sfllaw.livejournal.com]

Now that I think about it, you build an Array of Memberships, and optionally have references to these Memberships in each Group and Person. This allows for fast lookups, no matter how you traverse things.