On Sun, Feb 10, 2013 at 11:33 PM, Simon Cross firstname.lastname@example.org wrote:
On Sun, Feb 10, 2013 at 2:32 PM, Nick Coghlan email@example.com wrote:
For those that don't recall the original discussion, the proposal is to add a new __init_class__ hook, invoked after the class object is created, but before the class decorators are applied. This provides a simple approach to inherited post-creation modification of classes, without the need for a custom metaclass.
Couldn't one just write a metaclass that calls __init_class__ for you?
And, indeed, that's what Zope did more than 10 years ago. The problem is that you're now locked in to that metaclass - metaclass conflicts become a permanent risk.
You also can't *add* a metaclass to public classes, the risk of introducing metaclass conflicts means that such a change is always backwards incompatible.
Adding __init_class__ is fine though, because that's no higher risk than adding a __new__ or __init__ method (it's actually lower risk, since the signature is always consistent).