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From: "RasikaSrinivasan@gmail.com" <RasikaSrinivasan@gmail.com>
Newsgroups: comp.lang.ada
Subject: package Ada.Tags
Date: Thu, 7 Jun 2012 13:36:32 -0700 (PDT)
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Date: 2012-06-07T13:36:32-07:00
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Friends

I have two types declared as follows:

with Ada.Calendar ;

package events is
    type events_record_type is abstract tagged 
      record
         time : ada.Calendar.time ;
      end record ;
   procedure show(event : events_record_type) ;
   
   type basal_delivery_event_type is new events_record_Type with
      record
         amount : float ;
      end record ;
   overriding
   procedure show( event : basal_delivery_event_type ) ;
   
   type bolus_delivery_event_type is new events_record_Type with
      record
         amount : float ;
      end record ;
   overriding
   procedure show( event : bolus_delivery_event_type ) ;
   
   type SMBG_event_type is new events_record_type with
      record
         amount : short_integer ;
      end record ;
   overriding
   procedure show( event : SMBG_event_type ) ;
   
end events ;

The following implementation in the body:



   procedure show (event : events_record_type) is
      use GNAT.Calendar.Time_IO;  
   begin      
      put( ada.Tags.Expanded_Name( event'tag ) );      
      put( gnat.Calendar.time_io.Image( event.time , gnat.Calendar.Time_IO.ISO_Date & " %T")) ;      
   end show;

gives me a compilation error:

"tag" attribute can only be applied to objects of class - wide type.

In the above, isnt event an object meeting this criterion?

clearly i am missing something. The question is I want to find out the equivalent of RTTI from C++. ie Which one if the derived types is it.

clues appreciated. srini