Re: [Boost-users] [bind] Doubt regarding the use of shared_ptr with boost.bind

Subject: Re: [Boost-users] [bind] Doubt regarding the use of shared_ptr with boost.bind
From: Igor R (boost.lists_at_[hidden])
Date: 2010-09-23 12:25:52

> m_ioService.post(m_strand.wrap(
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  boost::bind(&LogWriter::append,
> (*logWritersItr), _logMessage, _logLevelString)
> Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â  ));
>
> The second param of Bind, (*logWritersItr), is a shared_ptr of LogWriter's
> subclass. The signature of LogWriter::append() is as following:
>
> virtual void append(const std::string& _logMessage, const std::string&
> _logLevelString) = 0;
>
> Base on document at
> http://www.boost.org/doc/libs/1_44_0/libs/bind/bind.html, the way I use bind
> will duplicate a copy of that shared_ptr. Any idea when will the duplicated
> shared_ptr become invalid so that the reference count decreases by one?

bind() takes your shared_ptr by value, so it won't become "invalid".
After io_service executes your functor, it will be destroyed, so all
its internal copies of that shared_ptr will be destroyed as well.