Re: The extension of Is_Basic to unicode (about AI12-0260-1)

[ytomino <aghia05@gmail.com>]

On Wednesday, April 11, 2018 at 12:38:07 PM UTC+9, J-P. Rosen wrote:
> Le 11/04/2018 à 02:52, ytomino a écrit :
> > AI12-0260-1/04 Functions Is_Basic and To_Basic in Wide_Characters.Handling
> > I found inconsistency between existing Characters.Handling.Is_Basic and new Wide_Characters.Handling.Is_Basic.
> > 
> > Characters.Handling.Is_Basic in RM:
> > 
> >    True if Item is a basic letter. A basic letter is a character that is in one of the ranges 'A'..'Z' and 'a'..'z', or that is one of the following: 'Æ', 'æ', 'Ð', 'ð', 'Þ', 'þ', or 'ß'.
> > 
> > Characters.H.Is_Basic includes only alphabet, not include other symbols.
> > Is_Basic ('+') = False.
> > 
> > Wide_Characters.Handling.Is_Basic in AI:
> > 
> >   Returns True if the Wide_Character designated by Item has no Decomposition Mapping in the code charts of ISO/IEC 10646:2017; otherwise returns False. 
> >   
> > Wide_Characters.H.Is_Basic includes all un-decomposable characters, called as "base character" in Unicode world. It include the symbols.
> > Is_Basic ('+') = True.
> > 
> > Perhaps, Is_Basic must be defined as the intersection of the set of base characters *and the set of letters* (categorized as 'Ll', 'Lu', 'Lt', 'Lm', 'Lo'... in Unicode Character Database).
> 
> 
> Right, but the old definition was wrong and the new one is right. In
> general, Ada prefers to use existing standards rather than inventing its
> own special definitions. If you need to make sure that something is a
> letter, there is the Is_Letter function.
> 
> -- 
> J-P. Rosen
> Adalog
> 2 rue du Docteur Lombard, 92441 Issy-les-Moulineaux CEDEX
> Tel: +33 1 45 29 21 52, Fax: +33 1 45 29 25 00
> http://www.adalog.fr

> Right, but the old definition was wrong and the new one is right.

I agree with you on the point of the old definition is wrong.
However, should new function name be used for new definition?