Re: Position of "use"

[Adam Beneschan <adambeneschan@gmail.com>]

On Saturday, July 5, 2014 12:12:59 AM UTC-7, J-P. Rosen wrote:
> Le 05/07/2014 08:43, Victor Porton a �crit :
> 
> > What is the difference between
> 
> > with X; use X;
> > package Y is
> > end Y;
> 
> > and
> 
> > with X;
> > package Y is
> >    use X;
> > end Y;

> > ?
> 
> A use clause (as well as any declaration) is usable from where it
> appears up to the associated "end".
> 
> 
> In the first case, it will allow short names for other with/use clauses,
> while in the second case it will be effective only inside the package.

Not true.  This is illegal:

    with Ada;
    use Ada;
    with Strings.Unbounded;
    package X is ...

You can't use this as a substitute for "with Ada.Strings.Unbounded".

The visibility rules for context clauses are separate from visibility rules in other cases.  At the moment, I am not sure there is any difference at all between Victor's two examples; I'll have to study the rules carefully to make sure.  It's possible that there is a difference if there is a child package (package X.Child is ...), or if there is a pragma in the context clause.  I'll try to look at it later.

                             -- Adam