Re: Clarification for the application of GVariant/Glib::Variant maybe types

[Markus Elfring <Markus Elfring web de>]

> The description of the GVariantType has a little more explanation:
> http://developer.gnome.org/glib/stable/glib-GVariantType.html#glib-GVariantType.description

Thanks for this link. - I'm sorry that I did not find the following paragraph
earlier.

The first major change with respect to the D-Bus type system is the introduction
of maybe (or "nullable") types. Any type in GVariant can be converted to a maybe
type, in which case, "nothing" (or "null") becomes a valid value. Maybe types
have been added by introducing the character "m" to type strings.


By which (member) function can such a variable be marked to contain an unknown
value?
(Do I overlook a programming interface once more?)
http://developer.gnome.org/glibmm/2.30/classGlib_1_1VariantBase.html

Regards,
Markus