Re: [boost] [signals/threadsafe version] Atomic disconnects

From: Frank Mori Hess (frank.hess_at_[hidden])
Date: 2008-03-07 10:30:58

On Friday 07 March 2008 02:50 am, Johan Torp wrote:
> A typical signals n' slots
> use case  is - at least for me:
>
> signal<void()> sig;
>
> class Foo{
>   Foo() {
>     con = sig.connect(bind(&Foo::some_func, this));
>  }
>
>   scoped_connection con;
>
>   void some_func() {}
> };

To have the connection disconnect on the Foo object's destruction, you're 
supposed to pass a shared_ptr owning the object (either directly or 
indirectly) to slot::track() before connecting the slot.  This insures the 
object is not destroyed while a slot invocation is in progress (the signal 
converts its weak_ptr copy to a shared_ptr while the slot runs), and 
disconnects the slot when the tracked weak_ptr expires.  It does have the 
drawback that you often can't track connections made in the constructor 
though, since enable_shared_from_this doesn't work there.  I did provide 
postconstructible/deconstruct_ptr to support postconstructors, although it 
does all add up to a bit more typing.

I've attached an altered version of your example which does what I've 
described.

-- 
Frank