From mboxrd@z Thu Jan  1 00:00:00 1970
X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me
X-Spam-Level: 
X-Spam-Status: No, score=-1.3 required=5.0 tests=BAYES_00,INVALID_MSGID
	autolearn=no autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,d187dd741b987313,start
X-Google-Attributes: gid103376,public
From: "W. Wesley Groleau (Wes)" <wwgrol@PSESERV3.FW.HAC.COM>
Subject: Re: Ada/Motif problem
Date: 1996/08/28
Message-ID: <9608281459.AA06806@most>#1/1
X-Deja-AN: 177164847
sender: Ada programming language <INFO-ADA@LISTSERV.NODAK.EDU>
comments: Gated by NETNEWS@AUVM.AMERICAN.EDU
mailer: Elm [revision: 70.85]
newsgroups: comp.lang.ada
Date: 1996-08-28T00:00:00+00:00
List-Id: <comp.lang.ada>


If the Motif libs were compiled with gcc then the following should work
with GNAT:

   HW : constant String := "Hello World" & ASCII.NUL;

   begin

      Xt.Intrinsic.XtAddCallback ( pb,
                                   Motif.et_cetera,
                                   hello.et_cetera'access,
                                   HW'Address             );

as long as you ensure that HW is ALWAYS in scope.

I've obviously never tried it with Ada-83, but that method for
sending a string to C works with several C compilers and Ada-83 compilers.

OOPS, I just realized you're trying to send it BACK to Ada.  Yes, you lose
bounds info, but you can sort of get them back as follows:

in callback:

   Local_HW : contant String := String_From_C ( the_thing_that_came_from_C );

where String_From_C is provided (with a different name) by most vendors,
but is basically

   Temp : String ( 1 .. some_arbitrary_limit );
   for Temp'Address use the_thing_that_came_from_C;

...

   for I in Temp'Range loop
      if Temp(I) = ASCII.NULL then
         return Temp ( Temp'First .. I-1 );
      end if;
   end loop;

---------------------------------------------------------------------------
W. Wesley Groleau (Wes)                                Office: 219-429-4923
Hughes Defense Communications (MS 10-40)                 Home: 219-471-7206
Fort Wayne,  IN   46808                  (Unix): wwgrol@pseserv3.fw.hac.com
---------------------------------------------------------------------------