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From: Dmitry A. Kazakov <mailbox@dmitry-kazakov.de>
Newsgroups: comp.lang.ada
Subject: Re: Clause "with and use"
Date: Mon, 03 Nov 2003 11:47:29 +0100
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On Fri, 31 Oct 2003 22:02:03 +0100, Gautier Write-only
<gautier@fakeaddress.nil> wrote:

>Peter Hermann's post about number_base reminds me on a suggestion of mine
>about a "with and use" clause in AC ! Comments are welcome...
>Original proposal follows:
>____
>
>Proposal for a "with and use" clause 
>
> Hello! 
>
> Almost the only thing I find tedious in Ada is the obligation 
> to name twice packages you intend to _use_ in a context_clause. 
> I illustrate with examples two usual ways of organizing context clauses: 
>
> (A) 
>
> -- (1) With'ed only 
> with Ada.Command_Line; 
>
> -- (2) With'ed and Use'd 
> with Ada.Text_IO, Ada.Integer_Text_IO, Ada.Float_Text_IO; 
> use Ada.Text_IO, Ada.Integer_Text_IO, Ada.Float_Text_IO; 
>
> Problem: in practice the list pair (2) is a lot longer (many many lines) and 
>         becomes difficult to synchronize. It is also difficult then to 
>         _verify_ that the pair is consistent 
>
> (B) 
>
> -- (1) With'ed only 
> with Ada.Command_Line; 
>
> -- (2) With'ed and Use'd 
> with Ada.Text_IO;                       use Ada.Text_IO; 
> with Ada.Integer_Text_IO;               use Ada.Integer_Text_IO; 
> with Ada.Float_Text_IO;                 use Ada.Float_Text_IO; 
>
> Advantage: much easier to verify and transport across sources 
> Problem: the beginning of sources becomes awfully long. 

There was a [simpler / better] proposal that:

use A.B.C.D;

implies:

with A.B.C.D;

It was rejected. Does anybody remember why?

------------
It would be nice to have something like:

use all A.B.C.D; to abbreviate:

use A;
use A.B;
use A.B.C;
use A.B.C.D;

------------
OR, maybe it is worth to invent some mechanism to rename all declared
entities of a package within another package:

package A is
   type Something is ...;
   procedure Foo;
end A;

package B is
   procedure Bar;
end B;

with A, B;
package Proxy is
   rename all A;
      -- = subtype Something is A.Something;
      --    procedure Foo renames A.Foo;
   rename all B;
      -- = procedure Baz renames B.Baz;
end Proxy;

Now one can "use" Proxy to see both A.Foo and B.Baz.

---
Regards,
Dmitry Kazakov
www.dmitry-kazakov.de