[Python-Dev] new metaclass error condition checks
thomas at python.org
Fri Apr 20 15:56:02 CEST 2007
On 4/17/07, Jean-Paul Calderone <exarkun at divmod.com> wrote:
> I just noticed r53997 (from some unit tests it broke), which disallowed
> like this:
> class X(object):
> def __repr__(self):
> return "blah"
> class Y(X, type):
> class Z:
> __metaclass__ = Y
> Making X classic eliminates the TypeError, and is probably an acceptable
> in a lot of cases (at least as long as classic classes are available). I
> wonder if the ability to override type special methods like this was
> when the change was made, though?
Probably not, or at least not consciously. I think the point is that 'type'
and its subclasses are special enough that this warrants a separate 'X' that
inherits from 'type' rather than 'object'. Reduced reusability, but how
badly does this affect you in the real world, really?
Thomas Wouters <thomas at python.org>
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