//! [0]
QDBusInterface remoteApp( "com.example.Calculator", "/Calculator/Operations",
                          "org.mathematics.RPNCalculator" );
remoteApp.call( "PushOperand", 2 );
remoteApp.call( "PushOperand", 2 );
remoteApp.call( "ExecuteOperation", "+" );
QDBusReply<int> reply = remoteApp.call( "PopOperand" );

if ( reply.isValid() )
    printf( "%d", reply.value() );          // prints 4
//! [0]