[IronPython] Metaclass bug?

Dino Viehland dinov at exchange.microsoft.com
Wed Mar 7 17:58:42 CET 2007

Thanks for reporting this Sylvain.  I believe this is the same or very similar to bug #7594 (http://www.codeplex.com/IronPython/WorkItem/View.aspx?WorkItemId=7594).

The good news is that this is fixed in our internal v2.0 branch.  The bad news is the fix was close to re-writing the type system (also fixing type(type) is type).  That makes it fairly unlikely that we'll be able to back port this to v1.x without seriously destabilizing it.  But it will be fixed in the future.

-----Original Message-----
From: users-bounces at lists.ironpython.com [mailto:users-bounces at lists.ironpython.com] On Behalf Of Sylvain Hellegouarch
Sent: Wednesday, March 07, 2007 6:15 AM
To: Discussion of IronPython
Subject: [IronPython] Metaclass bug?

The following code:

class C(object):

class Meta(type):

class A(object):
    __metaclass__ = Meta

    def __init__(self, e, s):
        print "__init__ A"

    def __call__(self, e, s):
        print "__call__ A"

class B(object):
    def mount(self, c):
        a = A(c, "")

if __name__ == '__main__':
    b = B()

Python 2.5
$ python test.py
__init__ A

IronPython 1.1b1 (1.1) on .NET 2.0.50727.42
$ mono bin/ipy.exe test.py
Traceback (most recent call last):
  File test, line unknown, in Initialize
  File test, line unknown, in mount
TypeError: unbound method __call__() must be called with A instance as
first argument (got C instance instead)

It appears that because of the meta-class IP gets confused as to what to
call since the __init__ and __call__ gave the same signature.

- Sylvain

users mailing list
users at lists.ironpython.com

More information about the Ironpython-users mailing list