Re: [Boost-users] [signals2][review] The review of the signals2 library (formerly thread_safe_signals) begins today, Nov 1st

Subject: Re: [Boost-users] [signals2][review] The review of the signals2 library (formerly thread_safe_signals) begins today, Nov 1st
From: Frank Mori Hess (frank.hess_at_[hidden])
Date: 2009-02-18 09:33:56

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On Tuesday 17 February 2009, Nat Goodspeed wrote:
> Nat Goodspeed wrote:
> > I want my visitor to detect a bound boost::shared_ptr<anything>
> > and pass the shared_ptr to my new slot_type object's track() method.
>
> Frank, that functionality isn't specific to either boost::trackable or
> my own Trackable base class. Supposing we can resolve the problem of a
> bound copy of a shared_ptr (previous message in thread), couldn't the
> Signals2 library incorporate that logic itself?

I don't view the "dynamically replace bound shared_ptr with weak_ptr in 
incoming bind functor" idea as viable.  But if you mean the general feature 
of searching for some base class during connect and automatically tracking 
those objects, that might get added in the future.  I would do it strictly as 
an optional extension though, in seperate headers and only using the 
library's existing public interfaces.  It would add a free function findable 
by ADL that would look for the trackable base class when connecting, 
something like:

class shared_trackable: public enable_shared_from_this<shared_trackable>
{};

namespace bs2 = boost::signals2;

template<typename Signal, typename Func>
bs2::connection connect(Signal &sig, const Func &f)
{
  typename Signal::slot_type myslot(f);
  // apply visitor to f here which finds shared_trackable objects 
  // and tracks their owning shared_ptr...
  shared_trackable_visitor visitor(myslot);
  visit_each(visitor, f);
  return sig.connect(myslot);
}
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