Re: Some kind of repeating in Static_Predicate

[ytomino <aghia05@gmail.com>]

On Monday, June 4, 2018 at 3:26:56 PM UTC+9, Jacob Sparre Andersen wrote:
> ytomino <agh...@gmail.com> writes:
> 
> > I'm trying to use a constant table (but that is unstable and may be
> > changed in compile-time) in Static_Predicate.
> >
> >  Set : constant String := ('T', 'a', 'b', 'l', 'e');
> >  
> >  subtype T is Character
> >     with Static_predicate => (for some I of Set => X = I);
> 
> Why not admit that it is a Dynamic_Predicate?
> 
> Alternatively:
> 
>    type T is ('T', 'a', 'b', 'l', 'e');
> 
> Or:
> 
>    subtype T is Character
>       with Static_Predicate => (T in 'T' | 'a' | 'b' | 'l' | 'e');
> 
> Greetings,
> 
> Jacob
> -- 
> "people who live in glass houses shouldn't be throwing rocks
>  -- especially at those who don't live in glass houses"

Thanks. But I want to separate the table and the subtype...
As an example:

(A): a platform-depended private package

 private package Mylib.Platform_Depended is -- for POSIX
    Separators : constant String := ('/');
 end;

Or:

 private package Mylib.Platform_Depended is -- for Windows
    Separators : constant String := ('/', '\');
 end;

(B): using (A)

 private with Mylib.Platform_Depended;
 package Mylib.Path_Manipulators is
    Separators : constant String;
    subtype Directory_Separator is Character
       with Static_Predicate =>
          (for I of Separators => Directory_Separator = I); -- **error**
    function Compose (
       Path : String;
       Separator : Directory_Separator;
       Name : String) return String;
    ...
 private
    Separators : constant String := Platform_Depended.Separators;
 end;

The reason of it's not Dynamic_Predicate is, I wish compile-time warning if possible.