Re: array size

[Robert A Duff <bobduff@world.std.com>]

Robert Dewar <robert_dewar@my-deja.com> writes:

> In article <3851d15b_1@news1.prserv.net>,
>   "Matthew Heaney" <matthew_heaney@acm.org> wrote:
> > >   for Preset_Array_Type'Size use 6 * Frequency_Type'Size;
> >
> > Always do this for composite types:
> >
> >   Preset_Array_Type_Size : constant := 6 *
> Frequency_Type'Size;
> >   for Preset_Array_Type'Size use Preset_Array_Type_Size;
> 
> 
> This is incomprehensible advice, these are obviously equivalent.
> Both will of course be illegal if Frequency_Type'Size is not
> static ... Matthew what are you trying to say here?

I stared at that one for a long time before I realized -- I think what
he's trying to accomplish is that you can elsewhere refer to the size of
Preset_Array_Type in a static expression (perhaps in some other rep
clause).  "Preset_Array_Type'Size" won't work, because it's not static.
You obviously don't want to write "6 * Frequency_Type'Size" more than
once in the program.  He's come up with a coding convention that ensures
you can always say "Preset_Array_Type_Size" to get the size of an array
as a static expression.

- Bob