[Python-3000] yes to class decorators

[Josiah Carlson]

Greg Ewing <greg.ewing at canterbury.ac.nz> wrote:
> 
> tomer filiba wrote:
> 
> > we should also note that it's possible to replace "__metaclass__"
> > by a @metaclass decorator.
> 
> I don't think so. Your proposed technique for that seems to
> involve creating an ordinary class first, then taking it
> apart and recreating it using the specified metaclass.
> That smells very wrong to me.

I more or less agree, at least on the side of 'creating and destroying a
class is a waste', but here's some abuse that I couldn't help chuckling
over. No need to even bother constructing a class, but don't forget that
'return locals()' at the end!  (not that I'm advocating its [ab]use,
just something that made me smile)

 - Josiah

>>> def metaclass(*bases):
...     def class_factory(fcn):
...         return type(fcn.__name__, bases, fcn())
...     return class_factory
...
>>> @metaclass(object)
... def newclass():
...     def foo(self, arg):
...         print arg
...     return locals()
...
>>> newclass().foo('hello!')
hello!
>>>