Re: [SyncEvolution] [REVIEW REQUEST 2/7] GDBus GIO: add variant append support

On Fr, 2012-01-27 at 14:55 +0100, Mikel Astiz wrote: > +template<class V1, class V2 = append_visitor_dummy_type> struct append_visitor : public boost::static_visitor<> > +{ > + GVariantBuilder&builder; > + append_visitor(GVariantBuilder&b) : builder(b) {} > + void operator()(const V1&v) const > + { > + dbus_traits<V1>::append(builder, v); > + } > + void operator()(const V2&v) const > + { > + dbus_traits<V2>::append(builder, v); > + } > +}; I think this could be simplified to struct append_visitor : public boost::static_visitor<> { GVariantBuilder&builder; append_visitor(GVariantBuilder&b) : builder(b) {} template<class V> void operator()(const V&v) const { dbus_traits<V>::append(builder, v); } };

I'm wondering how it works, though. In libdbus, the iterator for the variant must be opened with the type of the *value* in the variant. Here the GVariantBuilder is opened with G_VARIANT_TYPE("v"), the type of the *variant* itself: static std::string getType() { return "v"; } ... static void append(GVariantBuilder&builder, const boost::variant<V> &value) { g_variant_builder_open(&builder, G_VARIANT_TYPE(getType().c_str())); boost::apply_visitor(append_visitor<V>(builder), value); g_variant_builder_close(&builder); } I checked with dbus-monitor, the resulting D-Bus message has "variant string" as type of value, as intended.