From: ake.ragnar.dahlgren@gmail.com
Subject: Access type to member procedure of instance (Object Oriented programming in Ada)
Date: Mon, 19 Nov 2012 01:59:42 -0800 (PST)
Date: 2012-11-19T01:59:42-08:00 [thread overview]
Message-ID: <9b0bcb37-8ae3-440f-af4f-a796702e4250@googlegroups.com> (raw)
Not sure if this has already been discussed but: Is it possible to define a pointer to a member procedure of an instance?
This problem has it's origin in the implementation of the MVC pattern for a GtkAda application. Consider the following:
package Some_Package is
type Message_Type is tagged null record;
procedure Print(Message : Message_Type);
end Some_Package;
package body Some_Package is
procedure Print (Message : Message_Type) is
begin
null;
end Print;
end Some_Package;
Then it is possible to create the following Main application that compiles just fine:
with Some_Package;
procedure Main is
Message : Some_Package.Message_Type;
begin
Message.Print;
end Main;
Is it possible to create a parameterless access type to the Message.Print procedure? The following application refuses to compile:
with Some_Package;
procedure Main is
Message : Some_Package.Message_Type;
Method_Ref : access procedure := Message.Print'Access;
begin
Method_Ref;
end Main;
The error message is: no selector "Print" for type "Message_Type" defined at some_package.ads:3
It is possible to create a workaround:
with Some_Package;
procedure Main is
Message : Some_Package.Message_Type;
procedure Method_Ref is
begin
Message.Print;
end Method_Ref;
begin
Method_Ref;
end Main;
Is there a better way? Or is this the optimal way?
Regards,
Åke Ragnar Dahlgren
next reply other threads:[~2012-11-19 9:59 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-19 9:59 ake.ragnar.dahlgren [this message]
2012-11-19 11:13 ` Access type to member procedure of instance (Object Oriented programming in Ada) Georg Bauhaus
2012-11-19 11:39 ` Brian Drummond
2012-11-20 11:43 ` Brian Drummond
2012-11-20 21:57 ` Randy Brukardt
2012-11-19 13:03 ` sbelmont700
2012-11-19 16:18 ` Adam Beneschan
2012-11-19 17:02 ` Peter C. Chapin
2012-11-19 18:23 ` Adam Beneschan
2012-11-19 20:57 ` Peter C. Chapin
2012-11-19 21:26 ` Dmitry A. Kazakov
2012-11-19 22:19 ` Adam Beneschan
2012-11-20 10:12 ` Dmitry A. Kazakov
2012-11-20 21:51 ` Randy Brukardt
2012-11-21 8:24 ` Dmitry A. Kazakov
2012-11-21 22:19 ` Randy Brukardt
2012-11-20 10:59 ` Brian Drummond
2012-11-19 20:22 ` ake.ragnar.dahlgren
2012-11-20 11:16 ` Brian Drummond
2012-11-19 20:52 ` ake.ragnar.dahlgren
2012-11-19 21:56 ` Dmitry A. Kazakov
2012-11-22 9:49 ` ake.ragnar.dahlgren
2012-11-19 22:13 ` sbelmont700
2012-11-19 23:59 ` Randy Brukardt
2012-11-20 0:05 ` Randy Brukardt
2012-11-20 1:00 ` Adam Beneschan
2012-11-20 21:38 ` Randy Brukardt
2012-11-20 23:43 ` Adam Beneschan
2012-11-21 22:12 ` Randy Brukardt
2012-11-22 1:59 ` Adam Beneschan
2012-11-29 2:43 ` Randy Brukardt
2012-11-20 0:52 ` Adam Beneschan
2012-11-20 21:34 ` Randy Brukardt
2012-11-20 11:28 ` Brian Drummond
2012-11-20 14:27 ` Georg Bauhaus
2012-11-20 15:52 ` Adam Beneschan
2012-11-22 9:47 ` ake.ragnar.dahlgren
2012-11-22 10:25 ` Dmitry A. Kazakov
2012-12-02 20:42 ` ake.ragnar.dahlgren
2012-12-03 11:21 ` Dmitry A. Kazakov
2012-12-03 20:21 ` ake.ragnar.dahlgren
2012-12-03 22:15 ` Dmitry A. Kazakov
2012-12-25 21:51 ` Gustaf Thorslund
2012-12-26 18:11 ` ake.ragnar.dahlgren
2012-11-22 12:13 ` Brian Drummond
2012-12-03 16:17 ` ake.ragnar.dahlgren
2012-12-03 21:56 ` Brian Drummond
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