From: "Rodrigo García" <rodrigo.garcia@epfl.ch>
Subject: Re: Problem Eliminating constructors
Date: Mon, 20 Jan 2003 12:39:04 +0100
Date: 2003-01-20T12:39:04+01:00 [thread overview]
Message-ID: <3E2BDFD8.4070805@epfl.ch> (raw)
In-Reply-To: 3e274cad$0$33929$bed64819@news.gradwell.net
Victor Porton wrote:
> package A is
>
> type A_Type is tagged
> record
> X: Integer;
> end;
>
> function Create(X: Integer) return A_Type; -- guess what is the body
>
> end A;
>
> Then I have
>
> type B_Type is new A.A_Type with
> record
> Y: Integer;
> end;
>
> Compiler requires me to override Create as the return type changes.
> But it is meaningless as now I need Create with two parameters
> instead of one.
>
> What to do?
You do not need a constructor for this simple case. This will create
an A_Type object and initialize X to value 5.
declare
My_A : A.A_Type := (X => 5);
Similarly, this will create a B_Type object with X=5 and Y=6.
declare
My_B : B_Type := (X => 5, Y => 6);
Alternatively, you can use discriminants as well:
type A_Type (I : Integer) is tagged
record
X : Integer := I;
end record;
And then:
type B_Type (J : Integer; K : Integer) is new A_Type (I => J) with
record
Y : Integer := K;
end record;
With this solution, you are forced to provide initial values in the
creation.
Rodrigo
next prev parent reply other threads:[~2003-01-20 11:39 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-01-17 0:19 Problem Eliminating constructors Victor Porton
2003-01-17 15:21 ` John English
2003-01-17 21:10 ` Victor Porton
2003-01-18 15:19 ` Simon Wright
2003-01-20 11:39 ` Rodrigo García [this message]
2003-01-20 21:07 ` Victor Porton
2003-01-21 9:44 ` Dmitry A. Kazakov
2003-01-21 19:01 ` Martin Krischik
2003-01-21 11:43 ` Rodrigo García
2003-01-21 15:03 ` Stephen Leake
2003-01-21 13:09 ` Victor Porton
2003-01-22 15:26 ` Rodrigo García
2003-01-21 18:38 ` Victor Porton
2003-01-23 17:08 ` Stephen Leake
-- strict thread matches above, loose matches on Subject: below --
2003-01-17 6:54 Grein, Christoph
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