From: rick H <rik_nntp@dsl.pipex.com>
Subject: Re: Instantiating private types with discriminants?
Date: Tue, 09 May 2006 14:48:44 GMT
Date: 2006-05-09T14:48:44+00:00 [thread overview]
Message-ID: <gZ18g.28779$Nb2.521756@news1.nokia.com> (raw)
In-Reply-To: QD08g.28768$Nb2.521930@news1.nokia.com
Thank you, Georg, Ludovic and Dmitri for your replies.
Now I know I won't get shouted at for asking novice questions, I have
another query for you experts, if you've got the time to have a look:
I'm trying to query the tag of a record, which I can do quite nicely,
provided I both "with Ada.Tags" and "use Ada.Tags". Just for the sake
of it, I tried to remove the "use Ada.Tags" statement, but I can't work
out how I would then specify the XXX'Tag attribute of a variable.
Here's an example that illustrates my problem ("if Var_A'Tag..." is the
problem line):
with Ada.Integer_Text_IO;
with Ada.Float_Text_IO;
with Ada.Tags;
-- use Ada.Tags;
procedure Simple_Case is
type General_T is tagged null record;
type Access_T is access General_T'Class;
type Type_A is new General_T with
record
Data : Integer;
end record;
type Type_B is new General_T with
record
Data : Float;
end record;
Var_A : Access_T; -- could be "new Type_A" or a "new Type_B"
begin
-- Var_A := new Type_A' (Data => 100);
Var_A := new Type_B' (Data => 100.0);
-- problem line:
if Var_A'Tag = Type_A'Tag then
Ada.Integer_Text_IO.Put ( Type_A (Var_A.all).Data);
elsif Var_A'Tag = Type_B'Tag then
Ada.Float_Text_IO.Put ( Type_B (Var_A.all).Data);
end if;
end Simple_Case;
next prev parent reply other threads:[~2006-05-09 14:48 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-09 13:17 Instantiating private types with discriminants? rick H
2006-05-09 13:45 ` Georg Bauhaus
2006-05-09 14:06 ` rick H
2006-05-09 13:56 ` Ludovic Brenta
2006-05-09 14:24 ` rick H
2006-05-09 19:48 ` Ludovic Brenta
2006-05-09 14:05 ` Dmitry A. Kazakov
2006-05-09 14:48 ` rick H [this message]
2006-05-09 15:20 ` Jerry Petrey
2006-05-09 15:42 ` rick H
2006-05-09 15:53 ` Avoiding use Ada.Tags (was Re: Instantiating private types with discriminants?) Alex R. Mosteo
2006-05-09 16:01 ` Instantiating private types with discriminants? Dmitry A. Kazakov
2006-05-10 7:42 ` rick H
2006-05-10 9:09 ` Ludovic Brenta
2006-05-10 11:49 ` Georg Bauhaus
2006-05-10 13:44 ` rick H
2006-05-10 14:21 ` Ludovic Brenta
2006-05-10 15:10 ` rick H
2006-05-10 15:45 ` Ludovic Brenta
2006-05-10 14:41 ` Dmitry A. Kazakov
2006-05-10 15:34 ` rick H
2006-05-10 19:01 ` Georg Bauhaus
2006-05-10 19:05 ` Ludovic Brenta
2006-05-10 21:52 ` Rick H
2006-05-11 1:17 ` Jeffrey R. Carter
2006-05-11 7:44 ` Dmitry A. Kazakov
2006-05-11 8:27 ` rick H
2006-05-11 10:28 ` Dmitry A. Kazakov
2006-05-11 15:59 ` Robert A Duff
2006-05-12 7:37 ` Dmitry A. Kazakov
2006-05-12 9:24 ` Georg Bauhaus
2006-05-12 12:40 ` Dmitry A. Kazakov
2006-05-12 18:25 ` Randy Brukardt
2006-05-09 19:57 ` "Use" and "=" for Tags (was: Re: Instantiating private types with discriminants?) Jeffrey R. Carter
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