Re: Accessibility checks

["Randy Brukardt" <randy@rrsoftware.com>]

"Bill Findlay" <yaldnif.w@blueyonder.co.uk> wrote in message 
news:CE0CF7DE.329A0%yaldnif.w@blueyonder.co.uk...
> On 18/07/2013 00:44, in article ks7a8v$4nj$1@loke.gir.dk, "Randy Brukardt"
> <randy@rrsoftware.com> wrote:
>
>> "Jeffrey Carter" <spam.jrcarter.not@spam.not.acm.org> wrote in message
>> news:ks718g$aim$2@dont-email.me...
>
>>> Brukardt, ARG member and editor of the ARM, claims that 'Access never
>>> works and 'Unchecked_Access is always required, bypassing the
>>> accessibility checks. While this is not entirely true, it's quite common
>>> that one must use 'Unchecked_Access, so we could do without these rules
>>> and checks in the majority of cases.
>>
>> That's not entirely true: I did find one (and only one) instance where I 
>> was
>> able to use 'Access in my code (it had to do with a library-level
>> initialization).
>
> Interesting.
>
> My projects have 37 occurrences of 'Access and only 2 of 
> 'Unchecked_Access.

I recall Tucker telling me (after one of my frequent rants about the 
uselessness of 'Access) that he used it quite often. He then deconstructed 
several possible uses for access values constructed from static objects, and 
noted that some of them fit 'Access very well, and others did not. (His 
description was much more useful than this summary, of course; he is so much 
better that me at being able to summarize ideas. That's one trait that I've 
never managed to learn, despite many examples; I'm almost always happy when 
Tucker jumps into a discussion because he often explains the issue much more 
clearly than I did. But I digress...)

I tend to use 'Access on parameters to for temporary storage during 
processing in a package (Claw does this extensively), and in that case, 
accessibility is completely in the way. We use finalization to ensure the 
saved values don't live too long, a static check is never going to work.

OTOH, creating values at initialization, for instance, works perfectly, and 
the static check is helpful. So this is a case where we have rules that help 
some programming usages and hinder others -- still not the best choice of 
programming rules.

                                    Randy.