Re: initialize an array (1-D) at elaboration using an expression based on the index?

[Phil Clayton <phil.clayton@lineone.net>]

On Oct 24, 5:40 pm, Shark8 <onewingedsh...@gmail.com> wrote:
> Interesting.
> It doesn't look like it would be very extensible into multidimensional
> arrays though.
>
> Perhaps something like an 'Initialize attribute [on the type, not the
> variables thereof] which would take an Access to Function returning
> that type. It would have to be called only in the case of K :
> Array_Type because K : Array_Type:= (Others => <>) is providing an
> initialization of the default value to all the elements [which is
> unlikely to match the initialization's value].
>
> However, it is the internals of the function which are interesting if
> this route were taken.  The indexings need to be discrete types,
> however they need not be numeric or even all the same type. This
> results in the following being valid:
>   Type A_HighSchool_Letterjacket_Type is Array (Size, Color,
> Character) of Byte; -- A jacket-maker's inventory for letter-jackets.
>
> So we can't have an "array" representing the indicies for use in the
> initialization-function.
> (ex: ---Invalid
>   For Index_1 in Index(1)'Range loop
>     For Index_2 in Index(2)'Range loop
>       For Index_3 in Index(3)'Range loop
>         -- do stuff for calculating the value stored;
>       end loop;
>     end loop;
>   end loop;
> )

Good point.  I think it is ok for multidimensional arrays given the
right interpretation of a "for expression" though.

In fact, it should probably be called a "for aggregate".  It looked
like Adam was suggesting that it would just be another case of
array_aggregate (4.3.3) in the syntax.  So a nested "for aggregate"
would, presumably, work as a subaggregate allowing multidimensional
arrays to handled.

Another way to think about this is that

  (for I in T => F(I))

would be equivalent to and interchangeable with the named aggregate

  (X1 => F(X1), X2 => F(X2), ...)

where X1, X2, ... are the elements of subtype T.  With that view, it
seems a fairly simple extension to the language from a technical
perspective.

Phil