Re: Visibility of Indexing aspects

[Shark8 <onewingedshark@gmail.com>]

On Saturday, July 14, 2018 at 8:18:38 AM UTC-6, Jere wrote:
> I was going through an Ada library and noticed that they
> were able to add an indexing aspect to a type in the private
> section of a package but have the indexing work for types
> declared using the public view of the type.  It's a neat feature,
> but I wasn't sure if this was intentional or a GNAT bug?
> I searched through sections 13.1 and 4.1.6 of the RM, but no
> mention that I could find of the private/public requirements
> for the Variable_Indexing and Constant_Indexing aspects.
> 
> Is there something I missed in the RM, is this a GNAT bug, or
> something else?

I'm not sure what your problem is; it's perfectly fine to attach the predicate in the Private section:
    Package Tmp_2 is
	Type K(<>) is private;
    Private
	Function Valid( Input : String ) Return Boolean;
	Type K is new String
	with Dynamic_Predicate => Valid( String(K) );
	
	Function Valid( Input : String ) Return Boolean is
	    (for all CH of Input => CH /= ' ');
    End Tmp_2;

In fact, the subprograms refereed to in the predicate don't need to be visible at the point of declaration:
    Package Tmp is
	Type K(<>) is private
	with Dynamic_Predicate => Valid( String(K) );
    Private
	Function Valid( Input : String ) Return Boolean;
	Type K is new String;
	
	Function Valid( Input : String ) Return Boolean is
	    (for all CH of Input => CH /= ' ');
    End Tmp;