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,e9f44aef4f5aee18,start
X-Google-Attributes: gid103376,public
From: Gautier <Gautier.deMontmollin@Maths.UniNe.CH>
Subject: Access to procedures
Date: 1999/06/25
Message-ID: <37737285.5CF9ED5F@Maths.UniNe.CH>#1/1
X-Deja-AN: 493745659
Content-Transfer-Encoding: 7bit
X-Accept-Language: en
Content-Type: text/plain; charset=us-ascii
MIME-Version: 1.0
Newsgroups: comp.lang.ada
Date: 1999-06-25T00:00:00+00:00
List-Id: <comp.lang.ada>

Hello, Reference Manual gurus!

I've encountered a stupid but sticky problem by implementing my
Unzip-Ada project. In the interactive versions of extract procedures,
I pass an access to a feedback procedure for display & interaction.

*But* whatever the way I nest and subtype the things, the compiler
(GNAT) tells me (certainly with good reasons):

"subprogram must not be deeper than access type"

even when it doesn't seem depper at all! So, my question is:
how to do it ?

The code in question is :

* in Unzip package spec :

 type feedback_proc is access
   procedure ( percents_done: in natural; user_abort: out boolean );

  procedure Extract(from : zip_info; what : String;
                    method     : out pkzip_method;
                    feedback   : feedback_proc );

* in a main program (one of many attempts!) :

  subtype local_feedback_proc is feedback_proc;

  procedure My_feedback( percents_done: natural; user_abort: out boolean
) is
    new_done_dots: natural:= (dots * percents_done) / 100;
    begin
      for i in done_dots .. new_done_dots loop
        Put('.');
      end loop;
      user_abort:= false;
    end My_feedback;

  -- My_feedback_access: constant local_feedback_proc:= My_feedback'access;

  procedure Do_Unzip is
    begin
...
          Extract( zi, Argument(i), method, My_feedback_access );
    end Do_unzip;

NB: a generic solution doesn't seem a solution as some packages,
basically non-generic, have to call the feedback procedure; making
the whole generic could become heavy.

-- 
Gautier

--------
http://members.xoom.com/gdemont/