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=-1.9 required=5.0 tests=BAYES_00 autolearn=ham
	autolearn_force=no version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,72113392dc4997bd
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2003-04-17 12:41:27 PST
Path: archiver1.google.com!postnews1.google.com!not-for-mail
From: mheaney@on2.com (Matthew Heaney)
Newsgroups: comp.lang.ada
Subject: Re: Subprogram Pointer in a Generic
Date: 17 Apr 2003 12:41:26 -0700
Organization: http://groups.google.com/
Message-ID: <1ec946d1.0304171141.31c6f4f7@posting.google.com>
References: <1ftiuys.1twhum2q9qa00N%claveman@grzorgenplatz.net>
NNTP-Posting-Host: 66.162.65.162
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 8bit
X-Trace: posting.google.com 1050608487 30004 127.0.0.1 (17 Apr 2003 19:41:27
 GMT)
X-Complaints-To: groups-abuse@google.com
NNTP-Posting-Date: 17 Apr 2003 19:41:27 GMT
Xref: archiver1.google.com comp.lang.ada:36247
Date: 2003-04-17T19:41:27+00:00
List-Id: <comp.lang.ada>

claveman@grzorgenplatz.net (Charles H. Sampson) wrote in message news:<1ftiuys.1twhum2q9qa00N%claveman@grzorgenplatz.net>...
> I'm using a procedure that takes a procedure pointer as an
> argument.  It's pretty standard stuff:
> 
>           type Parameterless_Proc_Ptr is access procedure;
>           procedure Register (The_Proc : in Parameterless_Proc_Ptr);
> 
> 
>      There are two questions.  (1) What are they trying to prevent by
> this restriction?  (2) Is there a more robust way of working around it?

The purpose of subprogram pointers in Ada95 is to implement callbacks,
e.g. for implementing a GUI.  You don't have full downward closures in
Ada95.

If you want to call a subprogram supplied by a caller, then use a
generic formal subprogram instead:

generic
   ...
package GP is 
   generic
      with procedure Op is <>;
   procedure Generic_Call_Op (...);
   ...
end GP;


Another possibility is to import the subprogram as a generic formal
subprogram of the generic package:

   generic
     with procedure Op is <>;
     ...
   package GP is ...;


Perhaps if you provided more information about what you're doing then
maybe we can give some more specific solutions.