Issue 5768: Concern about the mapping of valuetypes to Ada                                                                                                                                                          (ada-rtf)
Source: Daimler AG (Mr. Oliver M. Kellogg, oliver.kellogg@eads.com Oliver.Kellogg@t-online.de)
Nature: Uncategorized Issue
Severity: 
Summary: The IDL to Ada mapping version 1.2 (01-10-42) of valuetypes
causes serious problems when combined with other IDL constructs.
 
Here is an example:


// file: my_module.idl
module my_module {
 
   valuetype vtype {
      public short member;
   };
 
   typedef vtype array_of_vtype[10];
 
/* Further sources of problems:
 *
   struct struct_with_vtype {
      vtype smember;
   };
 
   union union_with_vtype switch (boolean) {
      case true:
         vtype umember;
   };
 */
 
};
 
The array_of_vtype cannot be mapped to Ada, neither can the
struct_with_vtype or union_with_vtype.
 
I propose a change to the mapping for valuetypes as follows:
 
" A valuetype shall be mapped to a package, or a nested package
  when the valuetype is declared within a module. "


For clarity, here is the mapping that I propose for the above
example:


-- file: my_module.ads
with CORBA.Value;


package my_module is


   package vtype is


      type Value_Ref is new CORBA.Value.Base with null record;


      Null_Value : constant Value_Ref;


      procedure Set_member
        (Self : in Value_Ref;
         To : in CORBA.Short);


      function Get_member
        (Self : in Value_Ref)
         return CORBA.Short;


   private
      -- elided
   end vtype;


   type array_of_vtype is array (0 .. 9) of vtype.Value_Ref;


end my_module;


The change of mapping also affects the naming rules for the
generated Value_Impl package because in Ada, it is not possible
to formulate child packages of nested packages.
I propose the following naming scheme for the Value_Impl
package:


The name of the Value_Impl package be formed from the name
of the value type mapped package with "_Value_Impl" appended.


Thus, the name of the Value_Impl package for the above example
would be: my_module.vtype_Value_Impl.

Resolution: 
Revised Text: 
Actions taken:
November 27, 2002: received issue
Discussion: 

End of Annotations:=====
Sender: oliver.kellogg@sysde.eads.net 
Date: Wed, 27 Nov 2002 10:29:07 +0100 
From: Oliver Kellogg <oliver.kellogg@sysde.eads.net> 
Organization: EADS Deutschland GmbH 
X-Mailer: Mozilla 4.76 [en] (X11; U; Linux 2.4.18-17.7.x i686) 
X-Accept-Language: en 
To: issues@omg.org 
Subject: Concern about the mapping of valuetypes to Ada 


The IDL to Ada mapping version 1.2 (01-10-42) of valuetypes
causes serious problems when combined with other IDL constructs.
 
Here is an example:


// file: my_module.idl
module my_module {
 
   valuetype vtype {
      public short member;
   };
 
   typedef vtype array_of_vtype[10];
 
/* Further sources of problems:
 *
   struct struct_with_vtype {
      vtype smember;
   };
 
   union union_with_vtype switch (boolean) {
      case true:
         vtype umember;
   };
 */
 
};
 
The array_of_vtype cannot be mapped to Ada, neither can the
struct_with_vtype or union_with_vtype.
 
I propose a change to the mapping for valuetypes as follows:
 
" A valuetype shall be mapped to a package, or a nested package
  when the valuetype is declared within a module. "


For clarity, here is the mapping that I propose for the above
example:


-- file: my_module.ads
with CORBA.Value;


package my_module is


   package vtype is


      type Value_Ref is new CORBA.Value.Base with null record;


      Null_Value : constant Value_Ref;


      procedure Set_member
        (Self : in Value_Ref;
         To : in CORBA.Short);


      function Get_member
        (Self : in Value_Ref)
         return CORBA.Short;


   private
      -- elided
   end vtype;


   type array_of_vtype is array (0 .. 9) of vtype.Value_Ref;


end my_module;


The change of mapping also affects the naming rules for the
generated Value_Impl package because in Ada, it is not possible
to formulate child packages of nested packages.
I propose the following naming scheme for the Value_Impl
package:


The name of the Value_Impl package be formed from the name
of the value type mapped package with "_Value_Impl" appended.


Thus, the name of the Value_Impl package for the above example
would be: my_module.vtype_Value_Impl.



-- 
Oliver M. Kellogg
Naval and Ground Operations (NGO2)
Systems and Defence Electronics
EADS Deutschland GmbH
D-89070 Ulm, Germany
e-mail: oliver.kellogg@sysde.eads.net
tel.: (+49) 731 392-7138
fax:  (+49) 731 392-5826