void slot_base::create_connection()
{
// Create a new connection object
basic_connection* con = new basic_connection();
/* nothrow */ {
// The signal portion isn't really necessary, except that we need a
// signal for the connection to be connected.
con->signal = static_cast<void*>(this);
con->signal_data = 0;
con->signal_disconnect = &bound_object_destructed;
}
// This connection watches for destruction of bound objects. Note
// that the reset routine will delete con if an allocation throws
data->watch_bound_objects.reset(con);
// We create a scoped connection, so that exceptions thrown while
// adding bound objects will cause a cleanup of the bound objects
// already connected.
scoped_connection safe_connection(data->watch_bound_objects);
// Now notify each of the bound objects that they are connected to this
// slot.
for(std::vector<const trackable*>::iterator i =
data->bound_objects.begin();
i != data->bound_objects.end(); ++i) {
// Notify the object that the slot is connecting to it
BOOST_SIGNALS_NAMESPACE::detail::bound_object binding;
(*i)->signal_connected(data->watch_bound_objects, binding);
// This will notify the bound object that the connection just made
// should be disconnected if an exception is thrown before the
// end of this iteration
BOOST_SIGNALS_NAMESPACE::detail::auto_disconnect_bound_object
disconnector(binding);
// Add the binding to the list of bindings for the connection
con->bound_objects.push_back(binding);
// The connection object now knows about the bound object, so if an
// exception is thrown later the connection object will notify the
// bound object of the disconnection automatically
disconnector.release();
}
// No exceptions will be thrown past this point.
safe_connection.release();
data->watch_bound_objects.set_controlling(true);
}
connection
signal_base_impl::
connect_slot(const any& slot_,
const stored_group& name,
shared_ptr<slot_base::data_t> data,
connect_position at)
{
// Transfer the burden of ownership to a local, scoped
// connection.
data->watch_bound_objects.set_controlling(false);
scoped_connection safe_connection(data->watch_bound_objects);
// Allocate storage for an iterator that will hold the point of
// insertion of the slot into the list. This is used to later remove
// the slot when it is disconnected.
#if defined(BOOST_NO_CXX11_SMART_PTR)
std::auto_ptr<iterator> saved_iter(new iterator);
#else
std::unique_ptr<iterator> saved_iter(new iterator);
#endif
// Add the slot to the list.
iterator pos =
slots_.insert(name, data->watch_bound_objects, slot_, at);
// The assignment operation here absolutely must not throw, which
// intuitively makes sense (because any container's insert method
// becomes impossible to use in an exception-safe manner without this
// assumption), but doesn't appear to be mentioned in the standard.
*saved_iter = pos;
// Fill out the connection object appropriately. None of these
// operations can throw
data->watch_bound_objects.get_connection()->signal = this;
data->watch_bound_objects.get_connection()->signal_data =
saved_iter.release();
data->watch_bound_objects.get_connection()->signal_disconnect =
&signal_base_impl::slot_disconnected;
// Make the copy of the connection in the list disconnect when it is
// destroyed. The local, scoped connection is then released
// because ownership has been transferred.
pos->first.set_controlling();
return safe_connection.release();
}