Modes (was unbounded_string)

["Andrew Carroll" <andrew@carroll-tech.net>]

> Message: 7
> Date: Fri, 10 Oct 2003 11:15:27 +0200
> From: Dmitry A. Kazakov <mailbox@dmitry-kazakov.de>
> Subject: Re: Modes (was unbounded_string)
> To: comp.lang.ada@ada-france.org
> Message-ID: <htqcov8rj5v1ii4aiad48sso0dhj0glcan@4ax.com>
> Content-Type: text/plain; charset=us-ascii
> 
> On Fri, 10 Oct 2003 02:27:19 -0600, "Andrew Carroll"
> <andrew@carroll-tech.net> wrote:
> 
[snip]
> The rule of thumb is: newer use pointers if there is an alternative.
> So:
[snip]
>Thus another rule: if a pointer, then when possible anonymous:
>    procedure Add (This: access X; Token: Unbounded_String); 
>       -- This will be a primitive subprogram of X
> 
[snip]
> The Ada way is not to create objects you do not need.

Okay, so now we're getting to the information I want to know.
The "rules of thumb" for the "Ada idiom".  Anyone got a list of 
"standardized rules of thumb for the Ada idiom"?