Another foreach idea.

[Kirk McDonald]

Kirk McDonald wrote:
> In short, all you need is a "range" function that returns an array of 
> integers, or (alternately) a generator... something like this:
> 

Oh! I did some thinking and improved it a little. It's a struct now, so 
it doesn't need to touch the GC. And factory functions are maybe a 
little more clear than static opCalls (also, there are two, now).

private import std.stdio;

struct range_struct {
public:
     int m_start, m_end, m_step;

     // Compares whether i has reached the end
     private bool cmp(int i) {
         if (m_step > 0 && i < m_end) return true;
         else if (m_step < 0 && i > m_end) return true;
         else return false;
     }

     int opApply(int delegate(inout int) dg) {
         int result = 0;
         for (int i=m_start; this.cmp(i); i+=m_step) {
             result = dg(i);
             if (result) break;
         }
         return result;
     }
}

range_struct range(int start, int end, int step=1) {
     range_struct r;
     r.m_start = start;
     r.m_end   = end;
     r.m_step  = step;
     return r;
}

range_struct range(int end) {
     return range(0, end, 1);
}

void main() {
     foreach(i; range(10)) {
         writefln("%s", i);
     }
     foreach(j; range(10, 20)) {
         writefln("%s", j);
     }
     foreach(k; range(0, 10, 2)) {
         writefln("%s", k);
     }
}

-Kirk McDonald