Re: Sinkability: usefull in language bindings ? [was: Re: Sinkability considered harmful]

[Tristan Van Berkom <tristan van berkom gmail com>]

muppet wrote:
[...]
> For a plain GObject:
>
>    $pixbuf = Gtk2::Gdk::Pixbuf->new (...);
>
> - C function returns object with one reference.
> - wrapper adds one reference.
> - binding knows that this function is a constructor, so it removes
>   one reference to ensure that the wrapper is the sole owner.
>
> and
>
>    $pixbuf = $pixbuf_loader->get_pixbuf;  # you don't own the return yet!
>
> - C function returns object with n refs.
> - wrapper adds one reference.
>
>
> Contrast this with a GtkObject:
>
>    $button = Gtk2::Button->new ("hi");
>
> breaks down into
>
> - C function returns object with one floating ref
> - wrapper refs and sinks, becoming sole owner.
>
> Whereas:
>
>    $child = $widget->get_child;
>
> breaks down into
>
> - C function returns sunken object with n refs.
> - wrapper refs and sinks.  was already sunk, so sink does nothing, and
>   C object gets another ref owned by the wrapper.

Excuse me but I still dont register, why can you assume that
a function returning a GtkObject cant return an added reference ?

The function could be a factory function that may decide to
return a fresh GtkObject, or alternatively return you an added
reference to a shared singleton GtkObject (for a random example).

Cheers,
                              -Tristan

Note that I make the assumption that you want to garbage collect
your wrapped objects when they run out of context or whatever
appropriate time.