Re: Ada 0x Wish List

[steve.folly@rdel.NOT-A-REAL.co.uk (Steve Folly)]

On 12 Feb 2001 08:39:18 +0100, Florian Weimer <fw@deneb.enyo.de>
wrote:

>"Peter Richtmyer" <pmr@efortress.com> writes:
>
>> 2) In a subroutine, would like to be able to declare variables that
>> are "persistent", like C "static" variables and only used by the one
>> subroutine.
>
>This feature wouldn't interoperate with tasking, so I think it's a bad
>idea.
>

But neither do global variables if you're not careful.  Just because
it's dangerous *if* you're using tasking, doesn't mean you should
prohibit it in the language. The LRM describes several areas
where doing things like that things will make a program erroneous.


There is a way to accomplish static/persistent variables in Ada...

Where, for example, you would want...

function Count return Natural is
   C : static Natural := 0;
begin
  C := C + 1;
  return C;
end;

Can be achieved ....

package Count_Package is 
   function Count return Natural;
end Count_Package

package body Count_Package is
   C : Natural := 0;
   function Count return Natural is
   begin
    C := C + 1;
    return C;
   end;
end Count_Package;

function Count return Natural renames Count_Package.Count;


-- 
SF.