Can we get rid of opApply?

[Max Samukha]

On Tue, 20 Jan 2009 12:23:58 +0300, "Denis Koroskin"
<2korden at gmail.com> wrote:

>One nice thing that opApply capable of is it can avoid heap activity by stack-allocating data during iteration.
>
>For example, given an array of ints, iterate over string representations of them:
>
>struct IntegersAsString
>{
>    void opAplly(int delegate(string s) dg)
>    {
>        char[16] temp;
>
>        foreach (i; array) {
>            int len = sprintf(temp, "%d", i);
>            int result = dg(temp[0..len]);
>            if (result != 0) {
>                return result;
>            }
>        }
>
>        return 0;
>    }
>
>    private int[] array;
>}
>
>int array = [1, 1, 2, 3, 5, 8, 13];
>
>// no heap allocation take place
>foreach (string s; IntegersAsString(array)) {
>    writeln(s);
>}
>
>How would you do that with ranges?

struct IntegersAsString
{
    private
    {
      int[] array;
      char[16] temp;
    }

    char[] head()
    {
        int len = sprintf(temp.ptr, "%d", array[0]);
        return temp[0..len];
    }

    void next()
    {
        array = array[1..$];
    }

    bool empty()
    {
        return array.length == 0;
    }
}

void main()
{
    int[] array = [1, 1, 2, 3, 5, 8, 13];

    // no heap allocation take place
    foreach (char[] s; IntegersAsString(array))
        writefln(s);
}