Re: some trivial questions?

["Dmitry A. Kazakov" <mailbox@dmitry-kazakov.de>]

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