Re: [Boost-users] [signals] Automatic connection management and MT

From: Frank Mori Hess (frank.hess_at_[hidden])
Date: 2007-02-02 16:38:52

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On Friday 02 February 2007 06:34 am, Timmo Stange wrote:
> The wrapper signals::track would expect a shared_ptr and transport
> a weak_ptr. The information could be collected with visit_each just
> like it is done now and the number of trackable objects would only
> be limited by boost::bind. 

Okay, I think I've got it now.  The signals::track() wrapper would return 
some class, call it signals::tracked for now, which is implicitly 
convertible into a weak_ptr.  The code in signal::connect() would use 
visit_each on the return value from bind to look for any signals::tracked 
objects inside, and if found store them as weak_ptrs associated with the 
connection.  Then any slots with expired weak_ptrs could be cleaned up 
when the signal is next emitted, or also in signal::connect() to prevent 
lots of dead connections from accumulating.  If we do cleanup in 
connect(), then I could get rid of the disconnect callback stuff I added, 
since it would be mostly redundant.

> I think it is acceptable that the client 
> code must maintain a shared_ptr to the tracked instance, as that's
> expressing rather well what is happening here (even though it
> doesn't really share the ownership, it shares information about the
> object).

It does share ownership, at least during the periods when the signal is 
actually running the slot.

- -- 
Frank
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