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From: rrw@ccird1.UUCP (Rick Wessman)
Newsgroups: net.lang.ada
Subject: Generic list processing
Message-ID: <457@ccird1.UUCP>
Date: Tue, 10-Jun-86 07:59:35 EDT
Article-I.D.: ccird1.457
Posted: Tue Jun 10 07:59:35 1986
Date-Received: Sat, 14-Jun-86 05:36:47 EDT
Organization: CCI Rochester Development, Rochester, NY
Keywords: generic
List-Id: <comp.lang.ada>

I'm trying to put together a generic list processing routine for
a graphics package. Each list that I use is doubly-linked, so I
figured that I could use the same template over and over. However,
when I tried to compile the package, I got the errors shown below.
Can anybody tell me what I'm doing wrong?

Here's the package:

generic
	type LIST_TYPE is private;
	type LIST_POINTER is access LIST_TYPE;
package LIST_OPS is

procedure DELETE (item: LIST_POINTER; head_of_list: in out LIST_POINTER);
end LIST_OPS;
package body LIST_OPS is

procedure DELETE (item: LIST_POINTER;
		head_of_list: in out LIST_POINTER) is
begin

if item = head_of_list and
	then head_of_list.all.next = head_of_list then
-------------------------^A                                                  ###
--### A:error: LRM 4.1.3: inappropriate prefix
	head_of_list := null;
	return;
end if;

-- Otherwise, reset the pointers in the list and free the
-- item.
item.all.previous.all.next := item.all.next;
--------^A                                                                   ###
--------------------------------------^B                                     ###
--### A:error: LRM 4.1.3: inappropriate prefix
--### B:error: LRM 4.1.3: inappropriate prefix
item.all.next.all.previous := item.all.previous;
--------^A                                                                   ###
--------------------------------------^B                                     ###
--### A:error: LRM 4.1.3: inappropriate prefix
--### B:error: LRM 4.1.3: inappropriate prefix

end DELETE;
end LIST_OPS;

			Thanks,
				Rick Wessman
				seismo!rochester!cci632!ccird1!rrw