d-programming-language.org

[Max Klyga]

On 2011-07-05 08:31:46 +0300, Dmitry Olshansky said:

> 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

Pointer arithmetic is not strictly necessary for a systems language. 
Several operating systems were written in Oberon. It has no pointer 
arithmetics. Should it be considered not a systems language?