Re: array of generic packages?

[Ludovic Brenta <ludovic.brenta@insalien.org>]

"a malkiel" writes:
> hi im somewhat new to ada. i've been trying to nut this one but can't seem 
> to. Would anyone know if defining an "array of generic packages" is 
> possible? What im looking for is something of the nature:
>
> type shape_type is (circle, triangle);
> package shapePointer(1) is new shape(circle);
> package shapePointer(2) is new shape(triangle);
>
> thanks in advance.
> ciao, andrew 

No, you cannot have an array of generic packages.  You can only have
arrays of objects; objects are constants and variables.  You can
create a generic package that declares a new type of arrays, like so:

generic
   type Element_Type is private;
package Generic_Arrays is
   type Array_Type is array (Positive range <>) of Element_Type;
end Generic_Arrays;

type Triangle is ...

package Arrays_Of_Triangles is
    new Generic_Arrays (Element_Type => Triangle);

My_Triangle : Triangle;
My_Array : Arrays_Of_Triangles.Array_Type := (1 => My_Triangle);

However, the generic package is not really all that useful if all you
want is to declare new array types.  You'd be better off doing just:

type Array_Of_Triangles is array (Positive range <>) of Triangle;
type Array_Of_Circles is array (Positive range <>) of Circle;

which does not require a generic.

-- 
Ludovic Brenta.