[Zope-dev] Product upgrades

[Tim Hicks]

> ...and, this is a good argument for hiding the data in your objects'
> attributes, and only accessing that data through method calls.
> Encapsulation and data hiding.

Steve,

I don't suppose you could explain in a bit more detail what you mean here.
I'm slightly struggling to get my head around the finer points of OO
programming (it'd be fair to say I've only really used python in a
procedural way so far).  How does what you describe above help to get around
the problem of an old instance being constructed with the old __init__ not
having the same attributes as the new instances?  Don't suppose you could
give me an example? :-)

cheers

tim