Re: Question: Combination of Access and Constraining

[Yuri <yuri@tsoft.com>]

Jeffrey Carter wrote:

> >>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 how efficient will be eventual comparison/argument
passing code resulting from such Null_Tp constant? Is it going to be
one-instruction comparison in ASM or much more?

For access argument and null it probably will be just on-liner
comparison and one liner passing argument.

Just curious )

Yuri.