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
