Variable-length stack allocated arrays

[Andrei Alexandrescu]

grauzone wrote:
> Andrei Alexandrescu wrote:
>> grauzone wrote:
>>> Andrei Alexandrescu wrote:
>>>> grauzone wrote:
>>>>> bearophile wrote:
>>>>>> void bar(int n) {
>>>>>>   scope int[] a = new int[n]; // stack-allocated
>>>>>>   foo(a);
>>>>>> }
>>>>>
>>>>> Why are you making such proposals, when one of the core developers 
>>>>> even thought about removing normal "scope"? It's almost 100% 
>>>>> guaranteed that nobody will listen.
>>>>>
>>>>> I personally find it a good idea to find new ways to reduce 
>>>>> producing memory garbage. The D GC is slow and bad, so you'd better 
>>>>> avoid it.
>>>>>
>>>>> Let's make this claim: it is impossible to write high performance 
>>>>> applications (that need to make use of dynamic memory allocation) 
>>>>> in D without resorting to "unsafe" techniques. That would include 
>>>>> allocating memory on the stack, or manually freeing memory.
>>>>
>>>> I write high-performance code in D without resorting to unsafe 
>>>> techniques. Much of my code allocates arrays only in the beginning 
>>>> and uses them throughout.
>>>
>>> I intended to exclude this case with applications "that need to make 
>>> use of dynamic memory allocation". But I guess this doesn't apply to 
>>> programs that only allocate on initialization.
>>>
>>> So, how about programs that allocate/release memory while doing 
>>> computations?
>>
>> "Oil is found in the minds of men."
> 
> Can you explain what this means in the context of the problem mentioned 
> above?

It means that if you start with the goal of making high performance 
applications safe, you may achieve that. One guaranteed way to not get 
there is to start with a claim that it can't be done.

That being said, I like stack-allocated and I asked Walter for a long 
time to introduce them in the language. They have their problems though.


Andrei