[Python-Dev] [RELEASED] Python 2.7 alpha 2 (original) (raw)

Jack Diederich jackdied at gmail.com
Tue Jan 12 04:53:24 CET 2010

On Mon, Jan 11, 2010 at 7:11 PM, Barry Warsaw <barry at python.org> wrote:

As an example, the one library I've already ported used a metaclass.  I don't see any way to specify that the metaclass should be used in a portable way. In Python 2.6 it's:

class Foo:  metaclass = Meta and in Python 3 it's: class Foo(metaclass=Meta): 2to3 made that pain go away.

[sidebar]

  1. the metaclass fixer was a PITA to implement.
  2. 95% of metaclass definitions searchable via google code were of the "metaclass = type" variety. The 2to3 patch exists only because of the few other uses.
  3. 100% of the module level assignments in public projects were the "metaclass = type" variety which is why there isn't a fixer for that. Also, a fixer would have been really, really ugly (munge every class definition in this module because there is a top level assignment).

-Jack

More information about the Python-Dev mailing list