safety model in D

[Rainer Deyke]

Andrei Alexandrescu wrote:
> First off: _all_ languages except C, C++, and assembler are or at least
> claim to be safe. All. I mean ALL. Did I mention all? If that was some
> ideology that is not realistic, is extremely difficult to achieve, and
> ends up too painful to use, then such theories would be difficult to
> corroborate with "ALL". Walter and I are in agreement that safety is not
> difficult to achieve in D and that it would allow a great many good
> programs to be written.

You're forgetting about all other system programming languages.  Also,
many of these claims to safety are demonstrably false.

> The text is very approachable and informative, and I suggest anyone
> interested to read through page 5 at least. I think it's a must for
> anyone participating in this to read the whole thing. Cardelli
> distinguishes between programs with "trapped errors" versus programs
> with "untrapped errors". Yesterday Walter and I have had a long
> discussion, followed by an email communication between Cardelli and
> myself, which confirmed that these three notions are equivalent:
> 
> a) "memory safety" (notion we used so far)
> b) "no undefined behavior" (C++ definition, suggested by Walter)
> c) "no untrapped errors" (suggested by Cardelli)


They are clearly not equivalent.  ++x + ++x has nothing to do with
memory safety.  Conversely, machine language has no concept of undefined
behavior but is clearly not memory safe.  Also, you haven't formally
defined any of these concepts, so you're basically just hand-waving.


-- 
Rainer Deyke - rainerd at eldwood.com