Re: gobject construction with parameter

[James Morris <jwm art net gmail com>]

On 31 January 2011 13:32, Jannis Pohlmann <jannis xfce org> wrote:

> > Can anyone point me in the direction of code examples where the
> > construction of the g object requires a parameter so I can see how to
> > do it please? - I can't make sense of the documentation.
>
> I usually do this by adding a construct or construct-only property to
> the object class and creating a my_object_new() function that takes a
> parameter for this property that I can then pass to g_object_new().
>
> Here's a simple example from Xfce's XDG menu library garcon: GarconMenu
> is the object and it needs a menu file (a GFile object) to be
> constructed properly. So what we did is to to install a construct-only
> property like this:
>
>  http://git.xfce.org/libs/garcon/tree/garcon/garcon-menu.c#n246

It looks straight forward at first glance but soon becomes apparent
it's not at all :/

I want to pass a const char** null terminated list of C strings -
which is obviously not a G_TYPE_FILE!
I thought maybe I could use G_TYPE_ARRAY but that results in:

GLib-GObject-CRITICAL **: g_param_spec_object: assertion `g_type_is_a
(object_type, G_TYPE_OBJECT)' failed

So I've no idea what to do there. It's as clear as mud; I'm a GObject newb.


> and write a _new() function that takes a GFile for this property and
> passes it to g_object_new():
>
>  http://git.xfce.org/libs/garcon/tree/garcon/garcon-menu.c#n459
>
> This property will not be available in the init function (e.g.
> garcon_menu_init) but if you want to do something with it before the
> object can be used by the outside world, you can do that by overriding
> the GObject constructed function like you do with finalize or
> get_property. In constructed, the construct and construct-only
> properties will be set and you can do something with them.

Anyway, thanks for making an effort to help.  I think the only way
anyone could provide any further help here would be to show me an
example that works using a const char ** null terminated list of c
strings as a parameter to the constructor.

I will most likely avoid GObject all together and do it the old
fashioned C way as this only seems to be making it more complex than
necessary.

Thanks,
James.