Struct with default ctor (Was: [dmd-beta] dmd 2.064 beta take 2)

[deadalnix]

On Sunday, 19 May 2013 at 13:13:07 UTC, Andrei Alexandrescu wrote:
> On 5/19/13 9:11 AM, deadalnix wrote:
>> It is both a race condition and a null problem.
>
> No, it's just a race condition.
>
>> And having non nullable
>> type would have been a compile time error instead of days of 
>> debugging.
>
> No, the race condition would have stayed.
>

That is ridiculous. non nullable would have made the bug non 
existent, and even without race condition the problem would 
exists. a reference is null, it container shared, then set to 
something else. You can put barriers all over the place to make 
that sequentially consistent that it wouldn't change anything and 
the bug would still arise.

You also never provided any convincing solution to the safety 
hole. We can't even add check only on some edges cases as D also 
have values types. The only solution we are left with that is 
really safe is to null check every dereference or give up on 
@safe.

I encourage you to look at this : 
http://www.infoq.com/presentations/Null-References-The-Billion-Dollar-Mistake-Tony-Hoare

Most new languages removed nullable by default, or limited its 
uses (scala for instance, allow for null for limited scope).

I once again want to get attention on the fact that GC change 
everything in regard to reference, and that the C++ situation is 
a bad example.

Idan Arye > Nil proposal make no sens in a statically typed 
language. And you'll find no better kind of null. We have all 
tools we need in D to work around null in library.