Re: accesing internal codes used for an enumeration

[Ted Dennison<dennison@telepath.com>]

In article <mailman.989244246.26083.comp.lang.ada@ada.eu.org>, Marius Amado
Alves says...
>
>I am trying to implement a lexicon (in the database sense) as an
>enumeration with a representation clause.
>
>Example lexicon:
>
>  Name <-> Code
>  -------------
>  Ping      123
>  Pong      456
>
>Implementation:
>
>  type Names is (Ping, Pong);
>  for Names use (Ping => 123, Pong => 456);

What this does is tell the compiler to use 123 as the actual bit pattern that
represents "Ping" when it is stored in memory (or perhaps on disk). There is no
way to get at that value, short of converting it to something else in an
"unchecked" manner. 

If all you want to do is make force a specific bit pattern on those objects when
they are stored, then this is the way to do it. If instead you just want a
mapping that you can use internally in your program, you would probably be
better off doing something like the following:

type Names is (Ping, Pong);
type Name_Integer_Mapping is array (Names) of Integer;
Name_Map : constant Name_Integer_Mapping := (Ping => 123, Pong => 456);


---
T.E.D.    homepage   - http://www.telepath.com/dennison/Ted/TED.html
          home email - mailto:dennison@telepath.com