Re: New Listener and EventSource interfaces

[Michael Meeks <michael helixcode com>]

Hi Torsten,

On Mon, 13 Nov 2000, Torsten Schulz wrote:
>   It just comes in my mind, that the event/listener interface was the
> first and most annoying source of cyclic references in StarOffice API.
> In common the client holds a reference to the server component and if 
> the client registers a listener, the server component refs the client 
> to.
>    
> +----------------+   addRef() after activation     +----------------+
> | client         | ------------------------------> | server         |
> | & listener     | <------------------------------ | & event source |
> +----------------+   addRef() after addListener()  +----------------+
>
> 
>   If the picture is right for Bonobo server, have you thought about the
> problem how the cyclic reference will be broken?
  
        Well; we certainly thought about the problem. Currently we have a
thin layer of insulation from reference counting issues such as this,
since we have 2 levels of ref-counting: CORBA and Bonobo, the very 
real problems of ref counting, how to deal with loops elegantly etc. I am
hoping can be put off until Bonobo 2.0.
  
        In this case, the event source owns the Bonobo refs on its
listeners and manages their lifcycles. If a listener needs to detach
itself on destruction this can be done by keeping a CORBA ref on the
event source and freeing it on destruction.
  
        So, now you share my pain :-) it's not nice, but it's the best we
can do with the current setup I think (?).
  
        Regards,
  
                Michael.

-- 
 mmeeks gnu org  <><, Pseudo Engineer, itinerant idiot