metaclasses

castironpi at gmail.com castironpi at gmail.com
Tue Mar 4 06:31:10 CET 2008


On Mar 3, 10:01 pm, Benjamin <musiccomposit... at gmail.com> wrote:
> On Mar 3, 7:12 pm, castiro... at gmail.com wrote:
>
> > What are metaclasses?
>
> Depends on whether you want to be confused or not. If you do, look at
> this old but still head bursting essay:http://www.python.org/doc/essays/metaclasses/.
>
> Basically, the metaclass of a (new-style) class is responsible for
> creating the class. This means when Python sees
> class Foo(object):
>     __metaclass__ = FooMeta
> class FooMeta(type):
>     def __new__(cls, name, bases, dct):
>        #do something cool to the class
>        pass
> It asks FooMeta to create the class Foo. Metaclasses always extend
> type because type is the default metaclass.

But you can stack class decorations, but not class metas.

@somethingcool1
@somethingcool2
class Foo:
   pass

* class Foo:
   __metaclass__= MetaCool1, MetaCool

* denotes malformed



More information about the Python-list mailing list