Setting array length to 0 discards reserved allocation?

[Jonathan M Davis via Digitalmars-d]

On Sunday, 27 July 2014 at 09:10:26 UTC, Jakob Ovrum wrote:
> On Sunday, 27 July 2014 at 08:49:43 UTC, Jonathan M Davis wrote:
>> As defined by the language, T[] is a dynamic array. As great 
>> as the article is, it was wrong in its use of the terminology, 
>> and that's what's caused a lot of the confusion and resulted 
>> in arguments over the difference between a dynamic array and a 
>> slice (there really isn't any). IIRC, both Walter and Andrei 
>> stated in that discussion that T[] is a dynamic array as far 
>> as D is concerned and that's not going to change. The article 
>> really should be updated to reflect the correct terminology. 
>> As far as D is concerned a slice and a dynamic array are the 
>> same thing when it comes to arrays. They're just different 
>> names for T[], and trying to treat them as different just 
>> causes confusion.
>
> Conflating both concepts with the same name is why the article 
> was so dearly needed in the first place.

Except that no concepts are being conflated. T[] is the dynamic 
array. There's a block of memory managed by the GC underneath, 
but it's completely hidden from the programmer. It is _not_ the 
dynamic array. It's just a block of memory managed by the GC 
which is used to manage the memory for dynamic arrays, and it has 
a completely different type from T[]. It's not even an array in 
the D sense. The block of memory is referred to by a pointer, not 
a D array.

It's talk of "which array" owns the memory and the like which 
causes confusion, and talking about the GC-managed block of 
memory as being the dynamic array and the T[] that the programmer 
sees as being the slice is just plain wrong. The T[] is both a 
slice and a dynamic array (because they're the same thing), 
whereas the block of memory is neither. I think that the fact 
that the article tried to call the underlying block of memory a 
dynamic array has caused a lot of unnecessary confusion.

- Jonathan M Davis