[PyQt] SIP: deriving a python class from a C++ ABC results in a TypeError exception

[Demetrius Cassidy]

I have a C++ class which is declared with pure virtual methods, but if I
derive from this class in python and implement the pure virtual methods, I
get an exception:
TypeError: pyvoip.opal.OpalPCSSEndPoint cannot be instantiated or
sub-classed

My python class is declared as following:

class PCSSEndPoint(OpalPCSSEndPoint):
  def __init__(self):
  super(OpalPCSSEndPoint, self).__init__()

def OnShowIncoming(self, connection):
return True

def OnShowOutgoing(self, connection):
return True

def GetMediaFormats(self):
  return []


SIP definitions:

class OpalPCSSEndPoint : OpalLocalEndPoint /Abstract/
{

/**Call back to indicate that remote is ringing.
If false is returned the call is aborted.

The default implementation is pure.
*/
virtual PBoolean OnShowIncoming(
const OpalPCSSConnection & connection /NoCopy/ ///< Connection having event
) = 0;

/**Call back to indicate that remote is ringing.
If false is returned the call is aborted.

The default implementation is pure.
*/
virtual PBoolean OnShowOutgoing(
const OpalPCSSConnection & connection /NoCopy/ ///< Connection having event
) = 0;

};

Now the base class of OpalPCSSEndPoint is also an ABC, as it derives from an
ABC but does not re-define the pure virtual function:

class OpalLocalEndPoint : OpalEndPoint /Abstract/
{
  ...
};

class OpalEndPoint /Abstract/
{
virtual OpalMediaFormatList GetMediaFormats() const = 0;
};

I tried removing  /Abstract/ from OpalLocalEndPoint, but it made no
difference.  Any idea what's wrong in this scenario? The only way this
works, is if I subclass OpalPCSSEndPoint in C++ and then in Python create a
class derived from my OpalPCSSEndPoint subclass.
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