[Twisted-Python] _Dereference problems with jelly, pb.Cacheable, and cyclic references

Sebastian Hanlon sebastian.hanlon at uleth.ca
Thu Jun 23 19:25:43 EDT 2005

I'm having problems trying to spread a data structure using 
pb.Cacheable. The general framework involves three classes: Alpha, 
Bravo, and Charlie. Alpha maintains a list of Bravos and Charlies. 
Bravos can reference Charlies and Charlies reference Bravos. When they 
get unserialized, though, some of the Charlies have _Dereference objects 
where references to Bravos should be. The Bravos themselves come across 
the wire just fine.

A simple example program is attached. To run it, first start the server 
by running 'python jelly-test.py server', then run the client with 
'python jelly-test.py client'. You should get a _Dereference in the list
of Charlies printed by the client, like such:

--cut here--
Bravo(0) [<__main__.RemoteCharlie instance at 0x00C14DA0>]
Bravo(1) [<__main__.RemoteCharlie instance at 0x00C14DA0>, 
<__main__.RemoteCharlie instance at 0x00C19058>]
Bravo(2) [<__main__.RemoteCharlie instance at 0x00C19058>]
Charlie(<twisted.persisted.crefutil._Dereference instance at 
--cut here--

Can anyone help? I'm running the latest Twisted SVN on Python 2.3.4.

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