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,fd8f3d2ebf73a4b7,start
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2001-11-21 07:17:53 PST
Path: 
 archiver1.google.com!news1.google.com!sn-xit-02!supernews.com!news.tele.dk!small.news.tele.dk!195.54.122.107!newsfeed1.bredband.com!bredband!uio.no!ntnu.no!not-for-mail
From: Preben Randhol <randhol+abuse@pvv.org>
Newsgroups: comp.lang.ada
Subject: Whether to raise exception or End_of_List function
Date: Wed, 21 Nov 2001 15:17:52 +0000 (UTC)
Organization: Norwegian university of science and technology
Message-ID: <slrn9vnh96.55u.randhol+abuse@kiuk0156.chembio.ntnu.no>
NNTP-Posting-Host: kiuk0156.chembio.ntnu.no
X-Trace: tyfon.itea.ntnu.no 1006355872 11717 129.241.83.82 (21 Nov 2001
 15:17:52 GMT)
X-Complaints-To: usenet@itea.ntnu.no
NNTP-Posting-Date: Wed, 21 Nov 2001 15:17:52 +0000 (UTC)
User-Agent: slrn/0.9.7.2 (Linux)
Xref: archiver1.google.com comp.lang.ada:16791
Date: 2001-11-21T15:17:52+00:00
List-Id: <comp.lang.ada>

Hi

I have made a simple double linked list that I use in the application I
develop. Before somebody suggest I use some other libraries I want to
say that I made this double linked list to learn Ada 95 and get aware of
different problems/aspects of implementing this, so at least for this
application I want to keep it for now.

The list code can be viewed here: http://www.pvv.org/~randhol/Ada95/List/
Note that the code is still rough, I haven't removed some debugging
functions/procedures etc...

I put this into a package:

   package Examine_List is
         new Double_Linked_List (Data_Type => Natural);

   Main_Examine : Examine_List.List_Type := Examine_List.New_List;

And use the Main_Examine. So far it has worked nicely, but now I came to
that at one place (at least) in my application I have to go from the
current position of the iterator until the end of the list. I cannot
know the current position of the list iterator so I cannot use a
for-loop. If I want to use a while loop however there are the problem of
knowing when the end of the list is reached. I guess I can make a
function End_of_List (which must also work if one try to backwards in
the list) or I can just raise an exception when the user tries to
step off the list.

My question is which is the better solution; Exception or a End_of_List 
function and which would have fewer side effects?

Thanks in advance.

Preben
-- 
 ()   Join the worldwide campaign to protect fundamental human rights.
'||}
{||'                                           http://www.amnesty.org/