Classes and templates

[Hefferman via Digitalmars-d]

On Monday, 31 October 2016 at 20:20:09 UTC, Meta wrote:
> [...]
>
> You can't use an un-instantiated template as a type anyway, 
> unlike Java. There the above is illegal because of `BubbleSort 
> b = ...`. The symbol BubbleSort by itself is not a type; you 
> have to instantiate it with template arguments to create a 
> type. So you *could* do it like this:
>
> BubbleSort!(typeof(arr)) b = new BubbleSort!(typeof(arr));
>
> But that's too verbose. There's need need to repeat ourselves. 
> You can instead use `auto` and omit the type of `b`, which will 
> be inferred from the right hand side:
>
> auto b = new BubbleSort!(typeof(arr));

Thanks! This compiled just fine...

[code]
import std.random;
import std.stdio;

void main()
{
     immutable uint N = 10_000;

     double[] arr = new double[](N);
     for (uint k = 0; k < N; k++) arr[k] = uniform(0, N);

     auto b = new BubbleSort!(typeof(arr));
     b.Sort(arr);
}

public class BubbleSort(T)
{
     private T[] a;
     private uint n;

     public void Sort(T)(T[] a) {
         n = a.length;
         bubblesort();
     }

     private void bubblesort() {
         bool sorted;

         do {
             sorted = true;
             for (uint k = 1; k < n; k++) {
                 if (a[k-1] > a[k]) {
                     T tmp = a[k];
                     a[k] = a[k+1];
                     a[k+1] = tmp;
                     sorted = false;
                 }
             }
             n--;
         } while (!sorted);
     }
}
[/code]

It gives a Range Violation upon executing, but I guess it's part 
of the algorithm....