[Dbus-cxx-devel] About string arrays

[Michał 'K. R. <mi...@rz...>]

Hi folks,

String arrays work on the server side, the only needed addition is

namespace DBus
{
  template<>
  std::string signature<std::vector<std::string> >()
  {
    std::string t; return DBUS_TYPE_ARRAY_AS_STRING + signature(t);
  }
}

After that I am able to register a method returning
std::vector<std::string> > and d-feet dbus debugger is able to call it
and get the correct result.


What I can't get to work is the client side. Without additional
specializations, calling a method proxy

::DBus::MethodProxy<std::vector<std::string> >::pointer f;
// ...
return (*f)();

causes the compiler to complain:

/usr/include/dbus-cxx-0.7/dbus-cxx/types.h:61: error: cannot convert
‘std::string’ to ‘DBus::Type’ in return

but after adding the following (weird) specialization:

namespace DBus
{
  template<> inline Type type<std::string>() { return TYPE_STRING; }
}

It compiles, but cannot call the method because of an exception:
MessageIterator: Extracting non fixed array into std::vector


I am new to DBus, but from this message I can guess that array of
strings is quite different than array of primitives, which in glib
bindings is reflected  by G_TYPE_STRV as opposed to G_FOO_ARRAY. If I
guess right, this requires the implementation to use
dbus_message_iter_open_container() instead of
dbus_message_iter_get_fixed_array() to read data.

This seems to be implemented in MessageAppendIterator

      template <typename T>
      void append( const std::vector<T>& v ) {
        this->open_container( CONTAINER_ARRAY,
DBus::signature<T>().c_str() );

        for ( size_t i=0; i < v.size(); i++ )
          *m_subiter << v[i];

        this->close_container();
      }

but not in MessageIterator, as the default

      template <typename T>
      std::vector<T> get_array()

uses forementioned dbus_message_iter_get_fixed_array().

Is specializing MessageIterator::get_array method a correct way to
implement reading string arrays from the message?

cheers
-- 
Michał 'Khorne' Rzechonek
http://rzechonek.net