Joakim Hove wrote: > I have used ctypes to wrap a C-library > [...] > Observe that the c_container_get_node() function does _not_ allocate > memory, it just returns a opaque handle to a node structure, still > fully owned by the container structure. [...] > > class Container: > def __init__(self , filename): > self.c_ptr = c_container_alloc( filename ) > > def __del__( self ): > c_container_free( self.c_ptr ) > > def get_node( self , node_id): > Node( c_container_get_node( self , node_id )) > > > class Node: > def __init__( self , c_ptr ): > self.c_ptr = c_ptr > > def __del__( self ): > pass > > > Now, a use scenario might be like this: > > 1. Instantiate a Container() instance. > 2. Instantiate a Node() instance with the Container.get_node() > function. > 3. Forget about the Container instance and work happily with the Node > instance. > 4. Out of the blue comes the gc - and then? Will the Node instance be > enough to protect the Container instance from beeing garbage > collected?
No. You should be able to even see that by logging calls to alloc/free of your library. > I thought maybe the get_node() function should have something like a > incref() call, and the Node.__del__() function a corresponding > decref()? Or ?? I'd add an "__owner" field to the node, initialised with the owning container instance. Uli -- Sator Laser GmbH Geschäftsführer: Thorsten Föcking, Amtsgericht Hamburg HR B62 932 -- http://mail.python.org/mailman/listinfo/python-list
