Pass a serial port as user data in a GTK callback handler?

[hreba <hreba@terra.com.br>]

Hi,

I am new to Ada and still overwhelmed by the complexity of the language.

My actual programming exercise has a GTK GUI, and I want a callback 
handler to communicate through a serial port, so I need to pass the port 
in my user data, which must be of

    type User_Type (<>) is private;

which means it must be nonlimited.

But GNAT.Serial_Communications.Serial_Port is limited:

    type Serial_Port is new Ada.Streams.Root_Stream_Type with private;
    type Root_Stream_Type is abstract tagged limited private;

I tried to pass a reference to the port, and it must be an "access all" 
(because it is not allocated by my, but a preexisting variable (hardware 
resource), as I understand it):

    port: access all GNAT.Serial_Communications.Serial_Port;

But then I get an error message

    "all" is not permitted for anonymous access types.

Is there a solution?
-- 
Frank Hrebabetzky		+55 / 48 / 3235 1106
Florianopolis, Brazil