Hi,
Currently in Glibmm GDBus it seems no straightforward way to dynamically cast VariantBase containing some signature with object paths (o) into strictly typed Variant container. I faced the problem when interpreting (casting) the result of standard DBus org.freedesktop.DBus.ObjectManager.GetManagedObjects() method call which return signature is a{oa{sa{sv}}} (note 'o'). Typed Variant in my code is defined like this:
Glib::Variant<std::map<Glib::ustring, std::map<Glib::ustring, std::map<Glib::ustring, Glib::VariantBase>>>>
but the Glib::VariantBase::cast_dynamic fails with bad_cast, because the type signature of the typed Variant is a{sa{sa{sv}}}, thats is, object 'o' is replaced with just 's'.
My question - is there some ready-to-use type which can be used as a parameter of Variant<> template to specify that the Variant holds an object path, not just ordinary string?
Of course, it is possible to create such a class in the client code like this (pseudo code):
class obj_path_t : public Glib::ustring;
template<>
class Variant<obj_path_t> : public Variant<Glib::ustring>
{
static const VariantType& variant_type() { return VARIANT_TYPE_OBJECT_PATH; }
};
so that typed Variant looks like this:
Glib::Variant<std::map<obj_path_t, std::map<Glib::ustring, std::map<Glib::ustring, Glib::VariantBase>>>>
and it actually works for me (cast_dynamic is OK), but IMO it should be provided by the Glibmm itself. Did I overlook something? Or this is just a missing feature?
BR, Andrey
