From: Jacob Sparre Andersen <sparre@nbi.dk>
Subject: Re: working with diferent instances of the same generic interface
Date: Thu, 10 Sep 2015 14:22:56 +0200
Date: 2015-09-10T14:22:56+02:00 [thread overview]
Message-ID: <87egi65uqn.fsf@adaheads.sparre-andersen.dk> (raw)
In-Reply-To: adaff0f1-2522-42ad-b51b-78952da33e9c@googlegroups.com
Aitor Alcrudo Sangros wrote:
> Hi, I'm not really specifically tring to make that code work as
> is. What I want to know is how can I work with different instances of
> the same generic interface, doing things like iterating over a
> collection of them. This is a minimal example of how I am
> (unsuccessfully ) tring to do so. Anyway this code compiles, then has
> a runtime exception.
Your problem is that you instantiate the same package much too often.
Here is a working "solution":
package Intro is
type Data_type is interface;
generic
type Readable_Data is abstract new Data_type with private;
package Readable is
type Readable_Element is interface;
subtype Readable_Class is Readable_Element'Class ;
function Get_Values (this : Readable_Element ) return Readable_Data'Class
is abstract;
end Readable;
type state is (OK,KO);
generic
with package Readable_Reporting is new Readable(<>);
use Readable_Reporting ;
package Reporting is
type Reporting_Element is interface and Readable_Element ;
subtype Reporting_Class is Reporting_Element'Class;
function Report (This :Reporting_Element ) return state is Abstract;
overriding function Get_Values (this : Reporting_Element ) return
Readable_Data'Class is abstract;
end Reporting;
end Intro;
with Intro;
package Instantiations is
package Readable_Basic is new Intro.Readable (Intro.Data_Type);
package Reporting_Basic is new Intro.Reporting (Readable_Basic);
end Instantiations;
with Intro,
Instantiations;
package A is
type SomeData is new Intro.Data_type with record
a :float;
end record;
package Readable_Some renames Instantiations.Readable_Basic;
package Reporting_Some renames Instantiations.Reporting_Basic;
type Element_type_A is
new Readable_Some.Readable_Element and Reporting_Some.Reporting_Element
with
record
data : SomeData := SomeData'(a => 0.0 );
end record;
subtype Element_type_A_Class is Element_type_A'Class;
overriding function Report(This : Element_Type_A ) return Intro.state is ( Intro.KO);
overriding
function Get_Values (this : Element_type_A ) return Intro.Data_Type'Class is
(this.data);
end A;
with Intro,
Instantiations;
package B is
type OtherData is new Intro.Data_type with record
a :float;
end record;
package Readable_Other renames Instantiations.Readable_Basic;
package Reporting_Other renames Instantiations.Reporting_Basic;
type Element_type_B is new Readable_Other.Readable_Element
and Reporting_Other.Reporting_Element
with record
data :OtherData;
end record;
subtype Element_type_B_Class is Element_type_B'Class;
function Get_Values (this : Element_type_B ) return Intro.Data_Type'Class is
(this.data);
function Report(This : Element_type_B ) return Intro.state is ( Intro.KO);
end B;
with Ada.Containers.Indefinite_Vectors;
with Intro,
Instantiations;
package Manager is
package Reporting_Basic renames Instantiations.Reporting_Basic;
use Reporting_Basic;
package Element_Vector is new
Ada.Containers.Indefinite_Vectors
(Index_Type => Natural,
Element_Type => Reporting_Basic.Reporting_Class);
use Element_Vector;
type Manager is tagged record
elements : Element_Vector.Vector;
end record;
procedure Add_Element(this : in out Manager ;
Element : in Reporting_Class );
end Manager;
package body Manager is
procedure Add_Element(this : in out Manager ;
Element : in Reporting_Class ) is
begin
this.elements.Append(Element);
end Add_Element;
end Manager;
with Ada.Text_IO;
with A, B, Manager;
procedure Test is
Man : Manager.Manager;
Elm1_ptr : A.Element_Type_A_Class := A.Element_Type_A'(Data => (A => 1.0));
Elm2_ptr : B.Element_Type_B_Class := B.Element_Type_B'(Data => (A => 2.0));
begin
Man.Add_Element (Manager.Reporting_basic.Reporting_Class(Elm1_ptr));
Ada.Text_IO.Put_Line ("1 worked.");
Man.Add_Element (Manager.Reporting_basic.Reporting_Class(Elm2_ptr));
Ada.Text_IO.Put_Line ("2 worked.");
end Test;
Notice how there's no need for access types.
Greetings,
Jacob
--
"Universities are not part of the nation's security organisation,
they are not the nation's research laboratory either: they are
the nation's universities." -- E.W. Dijkstra
prev parent reply other threads:[~2015-09-10 12:22 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-09-08 15:10 working with diferent instances of the same generic interface Aitor Alcrudo Sangros
2015-09-08 17:11 ` G.B.
2015-09-09 6:38 ` Jacob Sparre Andersen
2015-09-09 11:08 ` Aitor Alcrudo Sangros
2015-09-09 12:17 ` Egil H H
2015-09-09 12:41 ` Aitor Alcrudo Sangros
2015-09-09 13:10 ` Egil H H
2015-09-09 14:50 ` Aitor Alcrudo Sangros
2015-09-09 16:48 ` Egil H H
2015-09-09 19:04 ` Aitor Alcrudo Sangros
2015-09-09 19:16 ` Dmitry A. Kazakov
2015-10-01 16:45 ` Aitor Alcrudo Sangros
2015-10-01 19:29 ` Dmitry A. Kazakov
2015-10-01 20:09 ` Randy Brukardt
2015-09-13 18:22 ` Florian Weimer
2015-09-10 12:22 ` Jacob Sparre Andersen [this message]
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