On Sunday, 27 July 2014 at 13:03:13 UTC, Jakob Ovrum wrote:
On Sunday, 27 July 2014 at 12:03:05 UTC, Jonathan M Davis wrote:
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
This very thread is a testament to the fact that no, it's not
completely hidden, and it is the conflation that causes
confusion, and clarity only comes when the two concepts are
explained separately.
This matches my experience when I teach about D's arrays on IRC
too - people generally feel enlightened after reading the array
article.
It's debatable whether hamfisting dynamic array capabilities
onto a simple slice type was a good idea or not (T[new],
anyone?), but we should be as clear with the current situation
as possible. Pretending there isn't a problem is ignoring the
cries of D newbies everywhere. Please stop.
The array article does a great job explaining a lot about D
arrays, and it definitely has helped people understand them. But
it uses the wrong terminology, and that's my point. In D, T[] is
a dynamic array and a slice. As far as D is concerned, there is
no difference. T[] normally refers to a block of memory that the
GC manages, but that block of memory is not typed as a dynamic
array. And that's where the article gets it wrong.
- Jonathan M Davis
