>  > >> I do sometimes wonder what would happen if the ancestry array were
>  > >> writeable.  It could be interesting.  I haven't thought through the
>  > >> possible pitfalls.

...

>  Would you want to be able to switch ordering too?  I wonder what kind
>  of interesting evil could come of that...

You can play with this in Python. If you modify the __class__ magic
var you can change an object's class in real-time. When I first
discovered this, I posted on a Python list that it seemed like a
sportscar without a seatbelt, and got some very outraged responses
from Python programmers who felt passionately that it was one of the
language's best features. The most memorable response turned my words
around ("sportscar without a speed limit").

On the flipside, I also heard a story from a guy who found this kind
of thing heavily abused in some legacy bioinformatics code in Python,
and he was not happy about it. Objects would wander off into
particular methods and come back home completely transformed. It
sounded very confusing.

-- 
Giles Bowkett

Blog: http://gilesbowkett.blogspot.com
Portfolio: http://www.gilesgoatboy.org