Re: [Boost-Users] Signal/Slot connect copies slot (repost).

From: Peter Dimov (pdimov_at_[hidden])
Date: 2003-04-23 08:24:49

Jesper Bojesen wrote:
> I have a problem with the semantics of the the signal connect method.

[...]

> int main () {
>   // Connect a HelloWorld slot
>   HelloWorld hello;
>   std::cout << "Main world at " << (void *) &hello << std::endl;
>
>   boost::signal<void ()> sig;
>   sig.connect(hello);
>
>   sig ();
>
>   std::cout << "Thats all folks!\n";
>   return 0;
> }

[...]

> My problem is that the object signalled is not the same object that I
> subscribed
> to the signal.
>
> Is this really what was inteded ?

Yes.

> Is the any rationale behind this behaviour ?

Yes. Consider what would happen if hello were destroyed before the sig()
call.

> I am aware that I can get the behaviour that I expected if I create
> the slot using the bind function, however, I find the simpler syntax
> very nice, but its semantics are counter intuitive, and potentially
> very confusing.

Try sig.connect(ref(hello)) to request a reference to be stored.