Re: Array Help?

[stefan-lucks@see-the.signature]

On Wed, 14 Mar 2012, BrianG wrote:

> On 03/09/2012 03:48 AM, stefan-lucks@see-the.signature wrote:
> > On Thu, 8 Mar 2012, Randy Brukardt wrote:
> > [...]
> > > <stefan-lucks@see-the.signature>  wrote:
> >
> > > > 1. Testing
> > > >
> > > > When you declare
> > > >
> > > >   procedure Sort(Items: in out array(Positive range<>) of T)
> > >
> > > Let's hope you never do that, because anonymous types are the bane of Ada.
> > > And you surely can't do it today!
> >
> > OK, the real thing would look about like that:
> >
> >    generic
> >       type Element_Type is (<>);
> >       type Index_Type is (Positive range<>);
> >       type Collection_Type is array(Index_Type range<>) of Element_Type;
> >       with function "<"(Left, Right : Element_Type) return Boolean is<>;
> >
> >    function Sort(Items : Collection_Type) return Collection_Type;
> >
> > > > in a package specification, and you try to write a proper black-box
> > > > test,
> > > > you need *more* test cases then when you do the same with another
> > > > popular
> > > > language.
> > >
> > > Right. Bob's suggestion for some semi-constrained array subtype would fix
> > > that. But note that it was killed in Ada 95 in part because the
> > > implementation needed was essentially a record type with some sort of
> > > magic
> > > indexing. Which was a mess.
> >
> > Would it ease the implementation if you constrain the start index to some
> > fixed value, such as Index_Type'First?
> 
> If that's what you want, why can't you (in this case) define that in your
> generic parameters, rather than an index range (which already has a defined
> type)?

Good catch! I actually meant Positive'First.

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