More on C++ stack arrays

[PauloPinto]

On Monday, 21 October 2013 at 00:59:38 UTC, Jonathan M Davis 
wrote:
> On Sunday, October 20, 2013 09:33:36 Walter Bright wrote:
>> On 10/20/2013 7:25 AM, bearophile wrote:
>> > More discussions about variable-sized stack-allocated arrays 
>> > in C++, it
>> > seems there is no yet a consensus:
>> > 
>> > http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2013/n3810.pdf
>> > 
>> > I'd like variable-sized stack-allocated arrays in D.
>> 
>> They're far more trouble than they're worth.
>> 
>> Just use:
>> 
>>      auto a = new T[n];
>> 
>> Stack allocated arrays are far more trouble than they're 
>> worth. But what
>> about efficiency? Here's what I often do something along the 
>> lines of:
>> 
>>      T[10] tmp;
>>      T[] a;
>>      if (n <= 10)
>> 	a = tmp[0..n];
>>      else
>> 	a = new T[n];
>>      scope (exit) if (a != tmp) delete a;
>> 
>> The size of the static array is selected so the dynamic 
>> allocation is almost
>> never necessary.
>
> If that paradigm is frequent enough, it might be worth wrapping 
> it in a
> struct. Then, you'd probably get something like
>
> StaticArray!(int, 10) tmp(n);
> int[] a = tmp[];
>
> which used T[10] if n was 10 or less and allocated T[] 
> otherwise. The
> destructor could then deal with freeing the memory.
>
> - Jonathan M Davis

Well that's the approach taken by std::array (C++11), if I am not 
mistaken.

--
Paulo