[Python-3000] Metaclasses in Py3K

[Phillip J. Eby]

At 02:39 PM 12/16/2006 -0700, Steven Bethard wrote:
> > The main issue for me is that I think that its important to distinguish
> > between get/set operations that are done at class definition time, and
> > get/set operations that are done later, after the class is created.
>
>Why?  Can you explain your use case?  Everything I'd care to do would
>treat later get/set operations on the class in the same way.

The above was actually Talin's statement, but I agree that there are 
circumstances where you want to know when the contents of the class are 
essentially finalized:

1. Validation -- have a point at which it's an error to have *not* set 
certain things

2. Setup of data structures that are expensive or complex to update 
incrementally during the process of class construction

For both of these things you want to know when the class is "ready", so to 
speak, and they are easily accommodated with today's metaclass construction 
protocol.