[Boost-bugs] [Boost C++ Libraries] #10100: [signals2] trackable fails to disconnect slot on deletion

Subject: [Boost-bugs] [Boost C++ Libraries] #10100: [signals2] trackable fails to disconnect slot on deletion
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2014-06-06 15:47:45

#10100: [signals2] trackable fails to disconnect slot on deletion
------------------------------+----------------------
 Reporter:  wim@…             |      Owner:  fmhess
     Type:  Bugs              |     Status:  new
Milestone:  To Be Determined  |  Component:  signals2
  Version:  Boost 1.55.0      |   Severity:  Problem
 Keywords:                    |
------------------------------+----------------------
 I ran into a situation where boost.signals correctly tracks the lifetime
 of an object, whereas boost.signals2 fails to track the lifetime of the
 object.

 My best guess is that there is probably a shared_ptr somewhere in the
 stack trace of the 'fooer' slot invocation that can be replace by a
 weak_ptr. The assumption is that that shared_ptr keeps the connection
 alive while it should die.

 Full test demonstrating the problem:

 {{{
 #include <boost/signals2.hpp>

 class TrackedObject: public boost::signals2::trackable
 {
 public:
   TrackedObject() {
     fooer.connect(boost::bind(&TrackedObject::foo, this));
   }
   ~TrackedObject() { std::cout << "Deleted!" << std::endl; }
   void foo();

   boost::signals2::signal<void()> fooer;
 };

 class Tracker
 {
 public:
   Tracker::Tracker(TrackedObject *object)
   {
     connection_ = signal_.connect(boost::bind(&TrackedObject::foo,
 object));
   }
   bool deleted() const
   {
     return !connection_.connected();
   }
 private:
   boost::signals2::signal<void()> signal_;
   boost::signals2::connection connection_;
 };

 void TrackedObject::foo()
 {
   Tracker tracker(this);

   delete this;

   if (tracker.deleted())
     std::cout << "Object was deleted" << std::endl;
   else
     std::cout << "Object was not deleted" << std::endl;
 }

 int main(int argc, char **argv)
 {
   TrackedObject *t = new TrackedObject();
   t->fooer(); // does not work
   //t->foo(); // works
 }
 }}}

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/10100>
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