Re: Question: Combination of Access and Constraining

[Jeffrey Carter <jrcarter@acm.org>]

Papandopulo wrote:
>>Pointers are inherently bad. Why not:
> 
> If they are ingerently bad why they are in
> the language ?

"Inherently bad" is not how I would put. However, large-scale pointer 
use is known to be the source of a family of errors. Pointers are needed 
far less in Ada than in some other languages, and it is a good idea to 
avoid them when you can.

>>function Fn (Arg : Tp) return Natural;
> 
> I have to use access type here. Since this is
> simplified example. I have function accepting
> several such array arguments each of which is
> optional (null).

This is still not a requirement to use access types. You can still say

Null_Tp : constant Tp (1 .. 0) := (1 .. 0 => False);

function Fn (Arg1 : Tp := Null_Tp; Arg2 : Tp := Null_Tp; ...)
return Natural;

Here you have a function with several such array arguments, each of 
which is optional, and each of which is a null array if not explicitly 
specified:

Tp1 : Tp (1 ..    10) := ...;
Tp2 : Tp (1 .. 1_000) := ...;
X   : Natural;
...
X := Fn (Tp1);         -- All except Arg1 are null
X := Fn (Arg2 => Tp2); -- All except Arg2 are null
X := Fn (Tp2, Tp1);    -- All except Arg1 & Arg2 are null

and so on.

-- 
Jeff Carter
"Monsieur Arthur King, who has the brain of a duck, you know."
Monty Python & the Holy Grail