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
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