Static Constructors

[Jarrett Billingsley]

On Sun, Oct 5, 2008 at 5:32 PM, Gide Nwawudu <gide at btinternet.com> wrote:
> On Sun, 5 Oct 2008 15:31:38 -0400, "Jarrett Billingsley"
> <jarrett.billingsley at gmail.com> wrote:
>
>>On Sun, Oct 5, 2008 at 1:26 PM, Gide Nwawudu <gide at btinternet.com> wrote:
>>
>>> The following code outputs [0 4 2 3], is this a bug in D2?
>>>
>>> int n = 1;
>>> int[] data = [0,1,2,3,4].dup;
>>> writeln(data); // [0 1 2 3 4]
>>> data[n] = data[$-1];
>>
>>now data is [0 4 2 3 4]
>>
>>> data[$-1] = 0;
>>
>>now data is [0 4 2 3 0]
>>
>>> data.length = data.length - 1;
>>
>>now data is [0 4 2 3]
>>
>>> writeln(data); // [0 4 2 3]
>>
>>And that's right.
>>
>>What's the issue?
>
> My main issue was with eraseNth re-ordering elements, but if moving
> the end element over the nth is standard, then I suppose it's ok. I
> would have expected a 'stable' version, i.e. [0 2 3 4] as the result.
>
> Gide

It's the faster method is all.  If you want a stable remove, you can
either copy everything after the removed element down a slot, or you
can create a new array with "a[0 .. n] ~ a[n + 1 .. $]".  The former
requires less memory and less strain on the GC, and unless you have a
really fancy compiler that will autoparallelize the copy from the old
array into the new, the second solution will be no faster at copying
the data.