From: "Rick Santa-Cruz" <rick_santa_cruz75@msn.com>
Subject: problems with classes
Date: Thu, 30 Sep 2004 23:20:47 +0200
Date: 2004-09-30T23:20:47+02:00 [thread overview]
Message-ID: <cjhtc3$8ul$03$1@news.t-online.com> (raw)
Hi,
First of all I wanna thank all people in this group for the help. I am just
a beginner in Ada and before I started Ada, I thought that cause I know C++
very well, it would be easy for me to understand Ada (in fact I made this
experience with learning programmin languages like Java, Perl, C#, etc.
after working a lot with C++). But this assumption was totally wrong. The
syntax of Ada seems to me a bit strange, at least at the moment ;), but I am
working hard to become better in Ada...
Here are 2 examples of source-codes:
1. Source1:
package Source_1 is
type Parent_Class is tagged
record
Number: Integer;
end record;
type Child_Class is new Parent_Class with private;
procedure Parent_Proc(P: Parent_Class);
procedure Child_Proc(C: Child_Class);
private
type Child_Class is new Parent_Class with
record
Number2: Integer;
end record;
end Source_1;
---------------------------------------------------------------------
1. Source2:
package Source_2 is
type Parent_Class is tagged
record
Number: Integer;
end record;
type Child_Class is new Parent_Class with
record
Number2: Integer;
end record;
procedure Parent_Proc(P: Parent_Class);
procedure Child_Proc(C: Child_Class);
end Source_2;
My question is now, why in the seconde code-example I get an error, that
Parent_Class has to be declared ready, before I define the Child_Class? Why
I don't get this error in the first case, cause there I specify the
Child_Class with: "type Child_Class is new Parent_Class with private;",
before I declare the procedure of the class Parent_Class?
If this would be C++, I think I would know the answer... so in C++
"something like this" exists, too. It is called pre-definition of a type.
That means that, for example if I need the name of a type before I wanna
specify it, I can just write:
class MyType;
and specify it later. Is this the case in Ada too?
Thanks in advance,
Rick
next reply other threads:[~2004-09-30 21:20 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-30 21:20 Rick Santa-Cruz [this message]
2004-10-01 7:35 ` problems with classes Dmitry A. Kazakov
2004-10-01 18:41 ` Rick Santa-Cruz
2004-10-04 8:33 ` Dmitry A. Kazakov
2004-10-04 10:19 ` Martin Dowie
2004-10-01 7:58 ` Martin Krischik
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