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=unavailable autolearn_force=no version=3.4.4
Path: 
 eternal-september.org!reader01.eternal-september.org!reader02.eternal-september.org!news.eternal-september.org!feeder.eternal-september.org!aioe.org!.POSTED!not-for-mail
From: "Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: some trivial questions?
Date: Thu, 2 Nov 2017 09:27:45 +0100
Organization: Aioe.org NNTP Server
Message-ID: <oteku0$ek3$1@gioia.aioe.org>
References: <6a5368c5-f015-4dcb-9291-e77b40fa1bf1@googlegroups.com>
 <ff607ea1-9d64-441b-b5e6-1a4377a5a199@googlegroups.com>
NNTP-Posting-Host: lKHBldubgAWx1EqbQpQ5LQ.user.gioia.aioe.org
Mime-Version: 1.0
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Transfer-Encoding: 7bit
X-Complaints-To: abuse@aioe.org
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101
 Thunderbird/52.4.0
X-Notice: Filtered by postfilter v. 0.8.2
Content-Language: en-US
Xref: news.eternal-september.org comp.lang.ada:48698
Date: 2017-11-02T09:27:45+01:00
List-Id: <comp.lang.ada>

On 02/11/2017 02:19, tclwarrior@gmail.com wrote:

> i think every time you insert a use, you will most definitely add a 
> with> it just look to me, that this is a bit redundant to add two
> line, when one should do ... the compiler can should easily assume
> that
Yes. There is no reason why "with" could not be deduced from "use". E.g. 
it is no problem to move with out of the local scope:

    declare
       use Bar; -- Cannot have with Bar here, but who cares?
    begin
       ...

There is no problem to determine if "use" refers to a local package like:

    declare
       package Foo is new Boo;
       use Foo; -- Cannot with Foo, but again who cares?
    begin

It is historically so and also there is a great unjustified sentiment 
against "use" in Ada community. I have a theory that people are either 
lazy to design their package in a way to make it friendly for "use" or 
take too big dosages of generics (:-)). Ada generics are totally "use" 
unfriendly.

> i think in a program with a large import (use) list of libraries, this can
> save many lines and looks cleaner

This is rather a different issue. "Use" is not transitive. If you "use 
A" in B and then "use B" in C that does not make "use A" in C. In a 
great number of cases one would like to have transitive "use". In many 
other cases one would like to have it as it is. This is a long-standing 
problem of having to reusable "package interfaces".

-- 
Regards,
Dmitry A. Kazakov
http://www.dmitry-kazakov.de