Memory safety depends entirely on GC ?

[via Digitalmars-d]

On Tuesday, 24 February 2015 at 20:53:24 UTC, Walter Bright wrote:
> On 2/24/2015 10:00 AM, Andrei Alexandrescu wrote:
>> I also owe you apologies for not acknowledging that work. I 
>> find the proposal
>> too complicated for what it provides and that's the short and 
>> long of it. It's
>> easy to make a large and complex language addition to support 
>> any sensible
>> abstraction. That doesn't make it automatically good.
>
> My criticisms of it centered around:
>
> 1. confusion about whether it was a storage class or a type 
> qualifier.
>
> 2. I agree with Andrei that any annotation system can be made 
> to work - but this one (as are most annotation systems) also 
> struck me as wordy, tedious, and aesthetically unappealing. I 
> just can't see myself throwing it up on a slide and trying to 
> sell it to the audience as cool.
>
> 3. In line with (2), I want a system that relies much more on 
> inference. We've made good progress with the existing 
> annotations being inferred.
>
> 4. I didn't see how one could, for example, have an array of 
> pointers:
>
>     int*[] pointers;
>
> and then fill that array with pointers of varying ownership 
> annotations.
>
> 5. The (4) homogeneity requirement would mean that templated 
> types would get new instantiations every time they are used 
> with a different ownership. This could lead to massive code 
> bloat.
>
> 6. The 'return ref' scheme, which you have expressed distaste 
> for, was one that required the fewest instances of the user 
> having to add an annotation. It turned out that upgrading 
> Phobos to this required only a handful of annotations.
>
> 7. 'return ref' makes memory safe ref counted types possible, 
> finally, in D, without needing to upend the language or legacy 
> code. And as the example I posted showed, they are 
> straightforward to write. Only time and experience will tell if 
> this will be successful, but it looks promising and I hope 
> you'll be willing to give it a chance.

Thanks for summarizing your reasons. I knew that you were unhappy 
with 1 - 3); I wasn't aware of 4) and 5). I can't get into detail 
now, as it's already late at night here, but I'll try thinking 
about it tomorrow.

FWIW, Zach just wrote in another thread that he will have his own 
proposal ready soon, based on DIP25, with `scope` being a storage 
class. Let's see how this goes.