Subject: Re: [Boost-users] [signals2][review] The review of the signals2 library (formerly thread_safe_signals) begins today, Nov 1st
From: Nat Goodspeed (nat_at_[hidden])
Date: 2009-02-18 11:48:51
Frank Mori Hess 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, 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.
Sigh, yeah -- that would seem to call for a whole new boost::bind()
feature supporting copy-with-transformation.
> 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 separate 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>
> {};
If I understand correctly, we expect the coder to pass to boost::bind()
a plain pointer, a reference or a weak_ptr to a shared_trackable
subclass instance. None of those will artificially prolong the life of
that instance. However, using enable_shared_from_this lets your visitor
obtain a shared_ptr to pass to slot_type::track(). Yes?
It's still the case that if the coder passes to boost::bind() an actual
shared_ptr to the shared_trackable subclass instance, the
slot_type::track() mechanism becomes irrelevant because the object won't
die. That might warrant a note in the documentation for this feature.