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

From: Frank Mori Hess (frank.hess_at_[hidden])
Date: 2007-02-06 14:25:00

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On Tuesday 06 February 2007 10:23 am, Douglas Gregor wrote:
> On Feb 5, 2007, at 6:28 PM, Timmo Stange wrote:
> > I understand your dilemma, but this can't be solved unless we
> > decide to
> > use something completely different from shared_ptr. The idea is that
> > by connecting a slot to a signal, the lifetime tracking of bound
> > objects is started and as soon as all shared_ptr references go out of
> > scope, the slot is disconnected. Even if we could open up a loophole,
> > you could never start tracking from the constructor itself, as the
> > external shared_ptr reference to your object is only initialized when
> > the constructor returns. You would need a second call to the member
> > function to start tracking, in which case you can just as well set
> > up the connection there.
>
> Does enable_shared_from_this help at all?

You know I think it might, at least using a modified or derived version of 
it.  Apparently, shared_ptrs will call into objects derived from 
enable_shared_from_this in order to set their _internal_weak_this 
weak_ptr.  If we could hook into that call, we could have it call a 
virtual function called postconstruct(), and voila!  We have a 
postconstructer where signals can be connected to member functions with 
tracking, and there is no danger of a slot being called before the object 
is fully constructed.  Subclassing works relatively well too, the subclass 
just has to be sure to call its base class' postconstruct() call if it 
overrides it.

- -- 
Frank
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