Re: Does object renaming allow the view to be a copy?

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

"Robert Eachus" <rieachus@comcast.net> wrote in message 
news:1554966b-2882-4f1f-8cc8-be5a03e44ad0@googlegroups.com...
> On Monday, January 23, 2017 at 3:40:10 PM UTC-5, Randy Brukardt wrote:
>
>> IMHO, 'Address should only appear in a program that is interfacing to 
>> some
>> memory-mapped entity; else use some form of 'Access (or 
>> 'Unchecked_Access).
>
> Hmm.  My code has cases of:
>      for X'Address use at mod 4;

Looks like you are trying to set Alignment which Ada 83 didn't have. Set 
alignment directly, so your reader knows what you're doing.

> I've also broken abstractions by using 'Address to obtain access to the 
> details
> of an otherwise private type--those are old, and can be updated to use 
> child packages.

Correct.

> I also seem to recall that a lot of the NUMWG work uses address clauses 
> when pulling
> floating point numbers apart--and putting them back together.

Ada 95 says that Unchecked_Conversion can be by-reference, so the 
performance reason for not using UC in this case doesn't exist (assuming a 
friendly implementer). UC also doesn't force a compiler to abandon many 
useful optimizations (or do horrible analysis before allowing it).

> and I also have some mixed Fortran and Ada that uses at Foo'Address + 24 
> or the like to deal with
> Fortran common blocks that are really overlays. (For example, one 
> declaration has the common block
>                     as an array, another converts it to a vector.)

This falls under "interfacing to some memory-mapped entity"; I purposely 
didn't say "hardware" because sometimes software needs it too.

> Are all of these deprecated now?

All but the last can be done better with other constructs, IMHO. For the 
last, it's case-by-case what the best approach would be: you might need 
'Address.

                       Randy.