[Python.NET] Inheriting from abstract .NET class

Hello out there,

I'm trying to inherit from an abstract .NET base class in Python (2.7). I'm a Python n00b but from what I understood...

Here's what I managed to do in Python only and which works fine:

[File: room.py] -------
import abc

class Room(object):
    def __init__(self, door):
        self.door = door

    def open(self):
        self.door.open()

    def close(self):
        self.door.close()

    def is_open(self):
        return self.door.is_open()

class Door(object):
    __metaclass__ = abc.ABCMeta

    def open(self):
        if not self.is_open():
            self.toggle()

    def close(self):
        if self.is_open():
            self.toggle()

    @abc.abstractmethod
    def is_open(self):
        pass

    @abc.abstractmethod
    def toggle(self):
        pass

class StringDoor(Door):
    def __init__(self):
        self.status = "closed"

    def is_open(self):
        return self.status == "open"

    def toggle(self):
        if self.status == "open":
            self.status = "closed"
        else:
            self.status = "open"

class BooleanDoor(Door):
    def __init__(self):
        self.status = True

    def is_open(self):
        return self.status

    def toggle(self):
        self.status = not (self.status)

Door.register(StringDoor)
Door.register(BooleanDoor)
-------

Now, all I did was to replace the abstract base class Door by a C# representation:

[File: PythonAbstractBaseClass.dll] -------
namespace PythonAbstractBaseClass
{
    public abstract class Door
    {
        public virtual void Open()
        {
            if (!IsOpen())
                Toggle();
        }

        public virtual void Close()
        {
            if (IsOpen())
                Toggle();
        }

        public abstract bool IsOpen();
        public abstract void Toggle();
    }
}
-------

Removing Door from the Python part and importing it from the .NET assembly instead, I end up with this:

[File: room2.py] -------
import clr
import abc
from PythonAbstractBaseClass import Door

class Room(object):
    def __init__(self, door):
        self.door = door

    def open(self):
        self.door.open()

    def close(self):
        self.door.close()

    def is_open(self):
        return self.door.is_open()

class StringDoor(Door):
    def __init__(self):
        self.status = "closed"

    def is_open(self):
        return self.status == "open"

    def toggle(self):
        if self.status == "open":
            self.status = "closed"
        else:
            self.status = "open"

class BooleanDoor(Door):
    def __init__(self):
        self.status = True

    def is_open(self):
        return self.status

    def toggle(self):
        self.status = not (self.status)

Door.register(StringDoor)
Door.register(BooleanDoor)
-------

But this fails with the following error message:

    Door.register(StringDoor)
AttributeError: type object 'Door' has no attribute 'register'

From what I understood about abc.ABCMeta, this metaclass contributes the 'register' method. It seems that abstract C# classes do not come with the same metaclass. They instead come with metaclass "CLR Metatype" which obviously does not provide 'register'.

But if I drop the call to 'register', on instantiating one of the derived classes, I receive the error message

    sdoor = StringDoor()
TypeError: cannot instantiate abstract class

Is there a way to inherit from an abstract .NET class or is this is missing feature?

Thanks in advance,

Henning

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