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* Interfacing ADA to C++ classes with parameters
@ 2002-04-03 12:46 John Haddon
  2002-04-03 13:53 ` Sergey Koshcheyev
                   ` (2 more replies)
  0 siblings, 3 replies; 7+ messages in thread
From: John Haddon @ 2002-04-03 12:46 UTC (permalink / raw)




Dear All,

I'm having a problem writing an interface to a C++ class in which I want to
pass a parameter in addition to the object. I attach the package spec, the
main program and the C header file. The interface compiles and links with
the main program EXCEPT for TEST_INT_RET. On linkage, the following error is
given:

./ex6d_main.o: In function `ex6d_main__dispatch':
C:/PROGRA~1/GNAT/Examples_jfh/ex6d_main.adb:25: undefined reference to
`A::test_int_param(void)'

Why is this trying to refer to A::test_int_param(void) and not
A::test_int_param(integer,void)?

If the line calling test_int_param is omitted then the program links and
runs satisfactorily. I suspect that the problem is in the interface or
import function pragma parameters.

I am using Gnat 3.14p for Windows NT and GCC 2.95.3-5 for mingw as the C++
compiler. This examples is based upon EX6 in the GNAT documentation.

Any suggestions?

Many thanks in advance,


John

-----extract from souorce codes

package Ex6d_If is

   package A_Class is
      --
      --   Translation of C++ class A
      --

      type A is tagged
         record
            O_Value : Integer                   := 123;
            A_Value : Integer;                          -- := print(10);
            Vptr    : Interfaces.Cpp.Vtable_Ptr;
         end record;

      pragma Cpp_Class (Entity => A);
      pragma Cpp_Vtable (
         Entity      => A,
         Vtable_Ptr  => Vptr,
         Entry_Count => 7);

      --   Member Functions


      procedure Non_Virtual (This : in     A'Class );
      pragma Import (Cpp, Non_Virtual, "non_virtual__1A");
      pragma import_procedure (non_virtual,"non_virtual__1A",(A'class));


      function test_int_ret(This : in     A'Class)
      return integer;
      pragma Import (Cpp, test_int_ret, "test_int_ret__1A");

      function test_int_param(
            X    : in     integer;
            This : in     A'Class)
      return integer;
      pragma interface (Cpp, test_int_param);
-- IS THE FOLLOWING LINE CORRECT?
      pragma import_function(test_int_param,"
test_int_param__1A",(integer,A'Class),(integer));


      procedure Overridden (
            This : in     A );
      pragma Cpp_Virtual (Overridden,
         Vtable_Ptr  => Vptr,
         Entry_Count => 2);
      pragma Import (Cpp, Overridden, "overridden__1A");


      procedure Not_Overridden (
            This : in     A );
      pragma Cpp_Virtual (
         Entity      => Not_Overridden,
         Vtable_Ptr  => Vptr,
         Entry_Count => 4);

      pragma Import (Cpp, Not_Overridden, "not_overridden__1A");


      procedure My_Overridden (
            This : in     A );
      pragma Cpp_Virtual (
         Entity      => My_Overridden,
         Vtable_Ptr  => Vptr,
         Entry_Count => 6);--,      --  long form

      pragma Import (Cpp, My_Overridden, "my_overridden__1A");

      function Constructor return A'Class;
      pragma Cpp_Constructor (Entity => Constructor);
      pragma Import (Cpp, Constructor, "__1A");

   end A_Class;

end Ex6d_If;


--------------------------------
ex6d_main.adb ---------------------------------
with gnat.io;use gnat.io;
with ex6d_if;
procedure ex6d_main is

   use ex6d_if;
   use ex6d_if.A_Class;


   A_Obj : A_Class.A;

   procedure Dispatch (Obj : A_Class.A'Class) is
      x,y : integer := 98;
   begin
      put_line("In dispatch");
      put_line("calling non-virtual");
      Non_virtual (Obj);
      put_line("calling test_int_ret");
      x := test_int_ret(Obj);
      put("X=");put(x);new_line;
      put_line("calling test_int_param");
      x := test_int_param(y,Obj);
      put("X=");put(x);new_line;
      put_line("Calling overriden");
      Overridden (Obj);
      put_line("calling not_overridden");
      Not_Overridden (Obj);
      put_line("Calling my_overriden");
      my_Overridden (Obj);
   end Dispatch;

begin
   put("in ex6d_main");
   Dispatch (A_Obj);
end ex6d_main;



---- C Header file

class Origin {
 public:
  int o_value;
};

class A : public Origin {
 public:
  void    non_virtual (void);
  int     test_int_ret (void);
  int     test_int_param (int X);
  virtual void overridden (void);
  virtual void not_overridden (void);
  virtual void my_overridden (void);
  A();
  int   a_value;
};

________________________________________________________________


Dr. John F. Haddon, QinetiQ Fellow,

Centre for Robotics and Machine Vision,
X107 Building, Room 1032,
QinetiQ, Cody Technology Park, Farnborough, Hampshire, GU14 0LX, UK
Email:  jf_haddon@QinetiQ.com  Tel: 01252 395528; Fax: 01252 393942

Visiting Senior Fellow, CVSSP, University of Surrey.
Honorary Visiting Fellow, PANN, University of Exeter.
________________________________________________________________

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^ permalink raw reply	[flat|nested] 7+ messages in thread
end of thread, other threads:[~2002-04-05 19:15 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2002-04-03 12:46 Interfacing ADA to C++ classes with parameters John Haddon
2002-04-03 13:53 ` Sergey Koshcheyev
2002-04-04  8:18   ` John Haddon
2002-04-05 15:44     ` Robert Dewar
2002-04-05 19:15       ` Ted Dennison
2002-04-03 14:28 ` Mário Amado Alves
2002-04-03 19:01 ` Stephen Leake

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