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=-2.9 required=5.0 tests=BAYES_00,FREEMAIL_FROM,
	MAILING_LIST_MULTI autolearn=unavailable autolearn_force=no
	version=3.4.4
X-Google-Language: ENGLISH,ASCII-7-bit
X-Google-Thread: 103376,79bbf7e359159d0d
X-Google-Attributes: gid103376,public
X-Google-ArrivalTime: 2001-04-04 22:02:05 PST
Path: 
 supernews.google.com!sn-xit-03!supernews.com!cyclone2.usenetserver.com!news-out.usenetserver.com!newsfeed.icl.net!isdnet!enst!enst.fr!not-for-mail
From: Wilhelm.Spickermann@t-online.de (Wilhelm Spickermann)
Newsgroups: comp.lang.ada
Subject: RE: newbie can't get exceptions to work!
Date: Thu, 05 Apr 2001 06:59:23 +0200 (CEST)
Organization: ENST, France
Sender: comp.lang.ada-admin@ada.eu.org
Message-ID: <mailman.986446867.31184.comp.lang.ada@ada.eu.org>
Reply-To: comp.lang.ada@ada.eu.org
NNTP-Posting-Host: marvin.enst.fr
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 8bit
X-Trace: avanie.enst.fr 986446867 22692 137.194.161.2 (5 Apr 2001 05:01:07
 GMT)
X-Complaints-To: usenet@enst.fr
NNTP-Posting-Date: Thu, 5 Apr 2001 05:01:07 +0000 (UTC)
To: comp.lang.ada@ada.eu.org
Return-Path: <Wilhelm.Spickermann@t-online.de>
X-Mailer: XFMail 1.4.0 on Linux
X-Priority: 3 (Normal)
In-Reply-To: <3ACBE436.4B247767@nmt.edu>
X-Sender: 0211750756-0001@t-dialin.net
Errors-To: comp.lang.ada-admin@ada.eu.org
X-BeenThere: comp.lang.ada@ada.eu.org
X-Mailman-Version: 2.0.3
Precedence: bulk
List-Help: <mailto:comp.lang.ada-request@ada.eu.org?subject=help>
List-Post: <mailto:comp.lang.ada@ada.eu.org>
List-Subscribe: <http://ada.eu.org/mailman/listinfo/comp.lang.ada>,
	<mailto: comp.lang.ada-request@ada.eu.org?subject=subscribe>
List-Id: comp.lang.ada mail<->news gateway <comp.lang.ada.ada.eu.org>
List-Unsubscribe: <http://ada.eu.org/mailman/listinfo/comp.lang.ada>,
	<mailto: comp.lang.ada-request@ada.eu.org?subject=unsubscribe>
List-Archive: <http://ada.eu.org/pipermail/comp.lang.ada/>
Errors-To: comp.lang.ada-admin@ada.eu.org
X-BeenThere: comp.lang.ada@ada.eu.org
Xref: supernews.google.com comp.lang.ada:6493
Date: 2001-04-05T06:59:23+02:00


On 05-Apr-01 Jeff Shipman wrote:
...
> generic
>    LEN : NATURAL := 100;      -- Size of the stack (default 100
>    type ELM is private;       -- Used to store element type
> 
>    package GEN_STACK is
>       STACK_ERROR : exception;        -- Raised when something bad
> happens.
>       
>       procedure PUSH(E : in ELM);     -- Push E into the stack
>       procedure POP(E : out ELM);     -- Pop element from stack;
> store
> in E
>       
>       function  FULL return BOOLEAN;  -- Returns TRUE if stack is
...
>    exception
>       when STACK_ERROR =>
...
> When I try to compile, I get the following errors:
> 
> use_gen_stack.adb:214:12: "STACK_ERROR" is not visible
> use_gen_stack.adb:214:12: multiple use clauses cause hiding

What should the program do, if You write "PUSH(4)"? Should it push into
INT_STACK or INT2_STACK?

You have created six _different_ exceptions, which are all called
STACK_ERROR. The compiler cannot possibly know which one You try to
handle. You could use names like FLOAT_STACK.STACK_ERROR etc.

You will run into the same problems with the other entities of the
generic package.

Such a "generic abstract data object" is very practical if only one
instantiation is needed at every place of use. If You really need
several stack in interleaved usage, you need a "generic abstract data
type".

Wilhelm