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
