d-programming-language.org

[Dmitry Olshansky]

On 05.07.2011 1:10, bearophile wrote:
> Steven Schveighoffer:
>
>> Or, use a separate type which throws the errors if you wish.
> I have recently explained why this is not good enough, or even currently impossible:
> http://www.digitalmars.com/webnews/newsgroups.php?art_group=digitalmars.D&article_id=139950
>
>
>> I don't want
>> runtime errors thrown in code that I didn't intend to throw.  most of the
>> time, overflows will not occur, so I don't want to go through all my code
>> and have to throw these decorations up where I know it's safe.
> The idea is to add two switches to DMD that activate the integral overflows (one for signed and one for signed and unsigned). If you compile your code without those, the runtime tests will not happen.
>
>
>> Besides, D is a systems language, and has no business doing checks
>> on every integer instruction.
> This argument doesn't hold, Delphi and Ada too are system languages.
In case of Delphi that's a bit of  stretch to say least, e.g. it _still_ 
lacks normal pointer arithmetic:

<quote>
In Delphi 2009, pointer arithmetic, as usable for the  PChar  type (and  PAnsiChar  and  PWideChar), is now also possible for other pointer types. When and where this is possible is governed by the new  $POINTERMATH  compiler directive.

Pointer arithmetic is generally switched off, but it can be switched on 
for a piece of code using|{$POINTERMATH ON}|, and off again 
using|{$POINTERMATH OFF}|. For pointer types compiled with pointer 
arithmetic (pointer math) turned on, pointer arithmetic is generally 
possible.

Apparently, in/Delphi 2009/, the new pointer arithmetic doesn't work as 
intended for pointers to/generic/types yet. Whatever type the parametric 
type is instantiated as, indices are not scaled by|SizeOf(T)|, as expected.
</quote>
http://rvelthuis.de/articles/articles-pointers.html
also:
http://stackoverflow.com/questions/4303880/delphi-pointer-arithmetic

-- 
Dmitry Olshansky