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-Thread: 103376,68a59f01eb1998d3
X-Google-Attributes: gid103376,public
X-Google-Language: ENGLISH,ASCII-7-bit
Path: 
 g2news2.google.com!news3.google.com!news.glorb.com!peer1.news.newnet.co.uk!194.159.246.34.MISMATCH!peer-uk.news.demon.net!kibo.news.demon.net!news.demon.co.uk!demon!not-for-mail
From: Simon Wright <simon@pushface.org>
Newsgroups: comp.lang.ada
Subject: Re: Ada generics and private type operations
Date: Sat, 14 Oct 2006 10:48:28 +0100
Organization: Pushface
Message-ID: <m2fydrns7n.fsf@grendel.local>
References: <%GEXg.237659$1i1.167064@attbi_s72>
 <mailman.1.1160744826.4389.comp.lang.ada@ada-france.org>
 <1160771945.155748.244730@k70g2000cwa.googlegroups.com>
 <1160773480.393825.96390@b28g2000cwb.googlegroups.com>
NNTP-Posting-Host: pogner.demon.co.uk
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
X-Trace: news.demon.co.uk 1160819310 14111 62.49.19.209 (14 Oct 2006 09:48:30
 GMT)
X-Complaints-To: abuse@demon.net
NNTP-Posting-Date: Sat, 14 Oct 2006 09:48:30 +0000 (UTC)
Cancel-Lock: sha1:VN9VRmx2Fbpa44J5O9W7RhZG+5E=
User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.0.50 (darwin)
Xref: g2news2.google.com comp.lang.ada:6961
Date: 2006-10-14T10:48:28+01:00
List-Id: <comp.lang.ada>

"Adam Beneschan" <adam@irvine.com> writes:

> Silly me.  I got so distracted by the presence of bird tracks all over
> my source that I forgot: you *can't* say ">=" => ">=" five times in
> your instantiation, because the thing on the left of the => can't be
> ambiguous.
>
> In fact, if you have more than one "with function >=" in your generic
> formal, then you can't say ">=" => anything, even once.  Either you
> have to let all of them default, or you have to use positional notation
> when you're instantiating (12.3(9)).  Actually, it's occurred to me
> that maybe this was your problem?

This is possibly a case for generic signature packages.

   generic
      type T is private;
      with function ">=" (L, R : T) return Boolean is <>;
   package Type_Signature is end Type_Signature;

   with Type_Signature;
   generic
      with package A is new Type_Signature (<>);
      with package B is new Type_Signature (<>);
   package User is
      function "<" (L, R : A.T) return Boolean;
   end User;

   package body User is
      function "<" (L, R : A.T) return Boolean is
      begin
         return not A.">=" (L, R);
      end "<";
   end User;