Re: segfault with large-ish array with GNAT

[Jerry <lanceboyle@qwest.net>]

On Mar 19, 1:22 pm, "Jeffrey R. Carter"
<spam.jrcarter....@spam.acm.org> wrote:
> Brian Drummond wrote:
>
> > But code using the array can be written as normal, with a "my_array ... renames
> > my_array_ptr.all" clause to hide the pointer.
>
> Generally, after something like
>
> A : constant Array_Ptr := new Array_Type [(Low .. High)];
>
> You can use A just as if it were the array itself:
>
> B := A (A'First);
> A (A'First) := A (A'Last);
> A (A'Last) := B;
>
> --
> Jeff Carter

That is true when accessing array elements and slices but not for
indicating the entire array as a single entity such as in a subroutine
argument, e.g.

y := cos(x);

or

z := x + y;

with

function "+"   (Left, Right : Real_Vector) return Real_Vector;

which is from ARM G.3.1.

Using access variables without renaming, the above line would have to
be written

y := cos(x.all);

and

z.all := x.all + y.all;

and in the algebraic-like calculations that are possible using
overloads the .all's clutter up the equation a bit. It's just a matter
of where you want to put the eye pollution. I have an extensive
library of subroutines including overloads that work with Real_Vector
and Complex_Vector from G.3 and either way (renaming or .all-ing)
works fine but on balance I think renaming is easier to read (and
probably easier to forget to release memory 8^( .)

Jerry