Alias this with array can only be used once

[Blake Anderton]

Why doesn't this work? I'm assuming I'm not fully understanding 
how "alias this" interacts with ranges (i.e. the range isn't 
being reset after count is finished with it), but I'm not sure 
how to fix this either:

import std.algorithm;

class ArrayContainer
{
     int[] values;
     this(int[] v) { values = v; }
     alias values this;
}

void main(string[] args)
{
     auto c = new ArrayContainer([1, 2, 3]);
     assert(count(c) == 3); //succeeds
     assert(c.length == 3); //FAILS - is actually zero
}