Re: copy GVariant

[Chris Vine <chris cvine freeserve co uk>]

On Tue, 08 Feb 2011 06:51:38 +0200
Povietkin Konstantin <povetkin k gmail com> wrote:
> В Вто, 08/02/2011 в 02:34 +0000, Chris Vine пишет:
> > On Mon, 07 Feb 2011 23:07:28 +0200
> > Povietkin Konstantin <povetkin k gmail com> wrote:
> > > I asked this question because i needed a c++ class that was using
> > > GVariant c-object.
> > > My solution is simple:
> > > 
> > >     GVariant * first;
> > >     GVariant * second;
> > > 
> > >     first = g_variant_new_string( "Тестовая строка" );
> > > 
> > >     second = g_variant_new_parsed( g_variant_print( first, TRUE )
> > > );
> > 
> > If you are programming in unwrapped glib, the normal thing would be
> > to copy the pointer and increment the reference count.
> > 
> > Chris
> > 
> > 
> 
> I need an object like Glib::GVariant and possibility to _copy_ data,
> not only referencing.

I should use Glib::Variant then, if you don't mind using version 2.27
of glibmm.  glib-2.28 is due out today so presumably glibmm-2.28 will
follow shortly thereafter.

But note that the copy constructor and assignment operator of
Glib::VariantBase also take a copy of the GVariant object and
increment the reference count.  GVariant objects are not intended to
be modified and there are no accessors for them which would permit that
(I think, I don't mind you showing me to be wrong).  This is reflected
in Glib::VariantBase which only enables modification by replacing the
entire underlying GVariant (with the Glib::VariantBase::init()
function).

You might also find Glib::VariantBase::get_normal_form() useful if you
want deep copying or referencing dependent on whether the variant is in
normal form, which is normally the only justification for carrying out a
deep copy operation.

Chris