[Python-Dev] Class decorators

[Greg Ewing]

Jack Diederich wrote:

> Using metaclasses also required gross hacks like checking
> for a 'DO_NOT_REGISTER' member for subclasses that wanted to inherit from
> a class that had a Register metaclass but didn't want to be registered.

I've just done something like this myself in the last
few days, and my solution was to have the registration
metaclass look for an attribute in the class's __dict__,
instead of using attribute access on the class, to
decide whether to register it.

That way the registerability doesn't get inherited,
and I get to choose individually for each class.

This of course may not be such a good idea if you
want registerability to *usually* be inherited, but
not always. In that case, you need some way of
saying when you don't want it, in which case a
do-not-register attribute doesn't seem so bad.
How else would you provide this information?

Still want class decorators, though. :-)

BTW, the system I'm working on is a response to
some hair-tearing problems I was experiencing
trying to pickle some of my data, and also to
address some disadvantages I see in using pickle
for long-term data storage. I'll write something
up about it if it works out...

-- 
Greg Ewing, Computer Science Dept, +--------------------------------------+
University of Canterbury,	   | Carpe post meridiam!          	  |
Christchurch, New Zealand	   | (I'm not a morning person.)          |
greg.ewing at canterbury.ac.nz	   +--------------------------------------+