overriding PublisherImpl for filtering outpout messages

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Hi guys,

I am preparing some multi-robot experiments and I would like to simulate some communication loss between robots. I have one ROS node on each robot supervising the mission execution. These nodes publish some information about their own execution status to all other robots to maintain a correct execution.

The point is that I would like to filter the published messages to simulate that e.g., robot 1 can communicate with robot 2 but not with robot 3: the published message should then be sent to r2 but not to r3.

Looking at the Publisher implementation (python version), I think this is possible to implement by redefining the publish method at rospy.topics._PublisherImpl.publish and filtering correctly the set of 'connections' of the publisher to send only to the relevant subscribers.

That's where I need help: I don't see any easy way to say to the publisher that I would like to use my new ComSimulationPublisherImpl(_PublisherImpl) implementation instead of the original _PublisherImpl class... Is there an easy way to do so without having to reimplement all the rospy.topics package?

Thanks,

Charles