Re: [Windows] Trash in sigc::trackable::callback_list_ when class is derived from Glib::Object

[John Emmas <john creativepost co uk>]

On 03/09/2014 10:17, Marcin Kolny wrote:
> Hi,
> Recently I've used glibmm on Windows, and I've met very strange 
> problem. Assume simple class:
>
> class Test : public Glib::Object
> {
> public:
>     Test()
>     {
>     }
> };
>
> When I instantiate this class, I see in debugger, that callback_list_ 
> of this object is not null (exactly, 0xfffffffc), but should be null. 
> It disallows me to use e.g. sigc::mem_fun.
> I saw in trackable constructor, that this field is set to zero, but 
> when I used debugger, and step by step through code, I noticed, that 
> callback_list_ changes at the beginning of Glib::Object constructor.

Hi Marcin.  I don't have any explanation but I can confirm that the same 
thing happens if I build your test sample with MSVC 8.  In fact AFAICT 
it happens with any glibmm object that's derived from ObjectBase.  For 
example, Glib::Interface and Gio::Icon both exhibit the same behaviour.  
However, if I derive my own classes from Glib::ObjectBase, they show 
'callback_list_' as being zero (immediately after construction).  
Unfortunately I'm not familiar enough with glibmm to know if what we're 
seeing is indicative of a problem (e.g. should you have called some 
initialization function before using GObject??)  Maybe sigc++ needs some 
initialization - or even glibmm itself?

John