Complex signal arguments are passed by value and needlessly copied in both stub and proxy

[martin-ejdestig]

Perhaps not that bad for a string, but e.g. have a signal that results in something like this in:

*_proxy.h:

    sigc::signal<void, Glib::DBusObjectPathString, std::map<Glib::ustring,Glib::VariantBase>> Foo_signal;

*_proxy.cpp:Proxy::handle_signal():

        if (parameters.get_n_children() != 2) return;
        Glib::Variant<Glib::DBusObjectPathString> base_arg1;
        parameters.get_child(base_arg1, 0);
        Glib::DBusObjectPathString p_arg1;
        p_arg1 = base_arg1.get();

        if (parameters.get_n_children() != 2) return;
        Glib::Variant<std::map<Glib::ustring,Glib::VariantBase>> base_arg2;
        parameters.get_child(base_arg2, 1);
        std::map<Glib::ustring,Glib::VariantBase> p_arg2;
        p_arg2 = base_properties.get();

        Foo_signal.emit((p_arg1), (p_arg2));

*_stub.cpp:

    void Foo_emitter(Glib::DBusObjectPathString, std::map<Glib::ustring,Glib::VariantBase>);
    sigc::signal<void, Glib::DBusObjectPathString, std::map<Glib::ustring,Glib::VariantBase>> Foo_signal;

void Stub::Foo_emitter(Glib::DBusObjectPathString arg1, std::map<Glib::ustring,Glib::VariantBase> arg2)
{
    std::vector<Glib::VariantBase> paramsList;

    paramsList.push_back(Glib::Variant<Glib::DBusObjectPathString>::create((arg1)));;
    paramsList.push_back(Glib::Variant<std::map<Glib::ustring,Glib::VariantBase>>::create((arg2)));;
    ...
}

Should perhaps add const & or && and std::move for non simple types where applicable.