Re: Persistence of limited tagged types

[mheaney@on2.com (Matthew Heaney)]

Nick Roberts <nickroberts@blueyonder.co.uk> wrote in message news:<oprm9kpdkkbqmqul@news.cis.dfn.de>...
> 
> If you really intend to be serialising limited types, I suspect that (both 
> theoretically and practically) you need to have intermediate non-limited 
> types to help you. Serialisation of a limited type will then involve: 
> conversion to and from a suitable non-limited type; serialisation of the 
> non-limited type.

All types ultimately comprise primitive scalar types (as integer,
float, etc) and simple composite types (string, etc), so yes there
will be non-limited types involved.

What you'll probably have to do is "default construct" an instance,
and then call read as a post-initialization step, e.g.

function Input (Stream : access Root_Stream_Type'Class)
  return T_Class_Access is

  Key : constant String := String'Input (Stream);

  I : constant Iterator := Find (Map, Key);

  Factory : constant Factory_Type := Element (I);
begin
  return Factory (Stream);
end;

The factory for T would look something like:

function New_T (Stream : access Root_Stream_Type'Class)
  return T_Class_Access is

  O : constant T_Access := new T; --default value
begin
  Read (Stream, O.all);  --post-initialization
  return T_Class_Access (O);
end;