Re: Using g_signal_connect in class

[Jean Bréfort <jean brefort normalesup org>]

Le samedi 19 juillet 2008 à 12:29 +0100, Chris Vine a écrit :
> On Tue, 15 Jul 2008 11:34:41 -0400
> "Vallone, Anthony" <anthony vallone lmco com> wrote:
> 
> > Only if the member function is static.  Calling a non-static member
> > function requires two addresses: the instance address and the function
> > address.  Whether its public or private doesn't matter because access
> > to function pointers is not checked by compilers.  I frequently do
> > something like this:
> > 
> > class SomeClass
> > {
> >   ...
> > private:
> >   ...
> >   static void staticCb(..., gpointer inInstance) {
> >     SomeClass* instance = (SomeClass*)inInstance;
> >     instance->callback(...);
> >   }
> >   void callback(...) {
> >     ...
> >   }
> >   ...
> >   void someFunc() {
> >     ...
> >     g_signal_connect(..., G_CALLBACK(&staticCb), this);
> >     ...
> >   }
> >   ...
> > };
> 
> This will work with gcc/g++ but it is not standard conforming, as
> static class functions do not have C linkage, and the C++ standard
> states that functions otherwise identical with C++ and C linkage are
> different types.
> 
> To be standard conforming you should use a friend function (if it needs
> access to private data) declared extern "C".
> 
> Chris

The extern "C" declaration is not needed.

Regards,
Jean