[Vala] ValueHash modeled after ValueList tuturial

[Franz Fasching <vala-list drfasching com>]

Hi Vala-List,

I'm trying to model a ValueHash after the ValueList example in the Vala
tutorial:

[Compact]
public class ValueHash : HashTable<string, Value?> {
[CCode (has_construct_function = false)]
protected ValueHash () {}
}

Compiling this yields (using valac-0.22):

error: unable to chain up to base constructor requiring arguments
protected ValueHash () {}
^^^^^^^^^^^^^^^^^^^

Searching the net I figured a call to the base() method is needed in the
constructor - but how?
...
protected ValueHash () { base(null, null); }
yields:
error: too few arguments to function ‘g_hash_table_new_full’
protected ValueHash () { base(null, null); }
^

...but:
protected ValueHash () { base(null, null, null); }
yields:
error: Too many arguments, method `GLib.HashTable<string,GLib.Value?>'
does not take 3 arguments
protected ValueHash () { base(null, null, null); }
^^^^^^^^^^^^^^^^^^^^^^

NB: As gobject already defines a ValueArray in the GLib namespace, a
ValueHash would come in handy there, but incidentally this is defined in
libsoup-2.4, but I don't want to introduce a dependency on libsoup in my
code.

Thanks a lot for any hints,
-Franz