Re: How to make Ada popular. Get rid of ";" at end of statement.

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

"Keith Thompson" <kst-u@mib.org> wrote in message 
news:lnh8785kge.fsf@kst-u.example.com...
> Lucretia <laguest9000@googlemail.com> writes:
>> On Thursday, 25 July 2019 08:26:29 UTC+1, Maciej Sobczak  wrote:
>>> > The one concrete reason I've ever heard for using C or C++ instead
>>> > of Modula-2 or Ada is that C/C++ allow you to perform pointer
>>> > arithmetic
>>>
>>> Really? I would never consider that reason myself.
>>
>> Me neither, but then you can do pointer arithmetic in Ada, you just
>> use normal numbers and convert to an address.
>
> I'm fairly sure there's no guarantee that the result of any such
> conversion (which would have to use Unchecked_Conversion or something
> equivalent, unless I've missed something) would be meaningful.

And there is in C?? ;-)

Package System.Storage_Elements includes operations for directly doing 
address arithmetic - you would have to do the multiplies on values of 
Storage_Offset (which is an integer type) and then add/subtract those from 
values of System.Address.

One could use Address_to_Access_Conversions to turn an address into an 
access value (which can then be dereferenced), as well as the reverse. 
That's better than Unchecked_Conversion as any representation differences 
can be handled properly, but admittedly there isn't much difference in the 
safety of the result.

In any case, pointer arithmetic can be done in Ada more-or-less directly. 
One wonders why it would be necessary (compiler optimizers can turn a lot of 
loops on arrays into pointer arithmetic code anyway, so there's likely to be 
little or no performance difference) - it sounds a lot like a combination of 
premature optimization and a convinient (and wrong) excuse not to consider 
Ada. (A lot of people out there are mainly looking for reasons not to use 
Ada or Rust or whatever language so that they can use whatever they have 
already decided on.)

                        Randy.