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From: "David Botton" <David@Botton.com>
Subject: Re: Binding a type to a union.
Date: 1999/11/22
Message-ID: <81d384$1g8o$1@news.gate.net>#1/1
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References: <slrn83jvkm.1mn.aidan@skinner.demon.co.uk>
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Newsgroups: comp.lang.ada
Date: 1999-11-23T03:55:48+00:00
List-Id: <comp.lang.ada>

You would do the following:

type foo_struct is
   record
      x : C.Int;
   end record;

type bar_struct is
   record
      x : C.char;
      y : some_enum_type;
   end record;

subtype Union_1_Range is Positive range 1..2;

type Union_1 (Which : Union_1_Range) is
   record
      case Which is
         when 1 =>
            foo : foo_struct;
         when 2 =>
            bar : bar_struct;
   end record;
pragma Unchecked_Union(Union_1);

type foo_type is
   record
     foo_bar : Union_1;
    end record;


Then you can access using:

my : foo_type;

my.foo_bar.foo.x := 1;

etc.

David Botton


Aidan Skinner wrote in message ...
>Can anybody tell me the correct way to give an Ada representation of a
>C union contained in a structure?
>
>Eg given a declaration in C of:
>
>struct foo
> {
>
>   union
>   {
>     struct
>     {
>       int x;
>     } foo
>
>     struct
>     {
>       char x;
>       some_enum_type y;
>     } bar
>
>   } foo_bar
> }
>
>What's the correct way of doing this given that x needs to be
>public?
>
>- Aidan