Re: sigc::mem_fun and Glib::RefPtr

[klaus triendl <klaus triendl eu>]

Am Fri, 05 Oct 2012 10:38:20 +0200
schrieb Kjell Ahlstedt <kjell ahlstedt bredband net>:

> All this seems incredibly complicated. Bug 495762 mentions an easier 
> way. See especially comment 9.
> 
> https://bugzilla.gnome.org/show_bug.cgi?id=495762#c9
> 
> It's cryptic. I haven't tested it myself, but I suppose someone else
> has.
> 
> Glib::RefPtr<MyClass> c;
> ...
> button.signal_clicked().connect(sigc::mem_fun(c.operator->(), 
> &MyClass::on_button));

The problem with my code is that Glib::RefPtr doesn't have a
dereferencing operator. Sorry, I didn't take this into account when I
used shared_ptr.

Yes, it's easier but all you do is to fetch the c-pointer from the
RefPtr. But you loose the reference counting: if the variable 'c'
goes out of scope you end up with a dangling pointer when there isn't
any other RefPtr alive.


A much easier solution than I've posted before is the following:

sigc::slot<void> f = 
    sigc::group(&MyClass::on_button, 
                sigc::group(&std::shared_ptr<MyClass>::operator->, c));
f();



greetings,
klaus